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mm: remove gup_flags FOLL_WRITE games from __get_user_pages() #22
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This is an ancient bug that was actually attempted to be fixed once (badly) by me eleven years ago in commit 4ceb5db ("Fix get_user_pages() race for write access") but that was then undone due to problems on s390 by commit f33ea7f ("fix get_user_pages bug"). In the meantime, the s390 situation has long been fixed, and we can now fix it by checking the pte_dirty() bit properly (and do it better). The s390 dirty bit was implemented in abf09be ("s390/mm: implement software dirty bits") which made it into v3.9. Earlier kernels will have to look at the page state itself. Also, the VM has become more scalable, and what used a purely theoretical race back then has become easier to trigger. To fix it, we introduce a new internal FOLL_COW flag to mark the "yes, we already did a COW" rather than play racy games with FOLL_WRITE that is very fundamental, and then use the pte dirty flag to validate that the FOLL_COW flag is still valid. Reported-and-tested-by: Phil "not Paul" Oester <[email protected]> Acked-by: Hugh Dickins <[email protected]> Reviewed-by: Michal Hocko <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Kees Cook <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Willy Tarreau <[email protected]> Cc: Nick Piggin <[email protected]> Cc: Greg Thelen <[email protected]> Cc: [email protected] Signed-off-by: Linus Torvalds <[email protected]>
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LGTM (identical changes to https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=19be0eaffa3ac7d8eb6784ad9bdbc7d67ed8e619 ) |
mischief
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Nov 1, 2016
commit b6bc1c7 upstream. Function ib_create_qp() was failing to return an error when rdma_rw_init_mrs() fails, causing a crash further down in ib_create_qp() when trying to dereferece the qp pointer which was actually a negative errno. The crash: crash> log|grep BUG [ 136.458121] BUG: unable to handle kernel NULL pointer dereference at 0000000000000098 crash> bt PID: 3736 TASK: ffff8808543215c0 CPU: 2 COMMAND: "kworker/u64:2" #0 [ffff88084d323340] machine_kexec at ffffffff8105fbb0 #1 [ffff88084d3233b0] __crash_kexec at ffffffff81116758 #2 [ffff88084d323480] crash_kexec at ffffffff8111682d #3 [ffff88084d3234b0] oops_end at ffffffff81032bd6 #4 [ffff88084d3234e0] no_context at ffffffff8106e431 #5 [ffff88084d323530] __bad_area_nosemaphore at ffffffff8106e610 #6 [ffff88084d323590] bad_area_nosemaphore at ffffffff8106e6f4 #7 [ffff88084d3235a0] __do_page_fault at ffffffff8106ebdc #8 [ffff88084d323620] do_page_fault at ffffffff8106f057 #9 [ffff88084d323660] page_fault at ffffffff816e3148 [exception RIP: ib_create_qp+427] RIP: ffffffffa02554fb RSP: ffff88084d323718 RFLAGS: 00010246 RAX: 0000000000000004 RBX: fffffffffffffff4 RCX: 000000018020001f RDX: ffff880830997fc0 RSI: 0000000000000001 RDI: ffff88085f407200 RBP: ffff88084d323778 R8: 0000000000000001 R9: ffffea0020bae210 R10: ffffea0020bae218 R11: 0000000000000001 R12: ffff88084d3237c8 R13: 00000000fffffff4 R14: ffff880859fa5000 R15: ffff88082eb89800 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 #10 [ffff88084d323780] rdma_create_qp at ffffffffa0782681 [rdma_cm] #11 [ffff88084d3237b0] nvmet_rdma_create_queue_ib at ffffffffa07c43f3 [nvmet_rdma] #12 [ffff88084d323860] nvmet_rdma_alloc_queue at ffffffffa07c5ba9 [nvmet_rdma] #13 [ffff88084d323900] nvmet_rdma_queue_connect at ffffffffa07c5c96 [nvmet_rdma] #14 [ffff88084d323980] nvmet_rdma_cm_handler at ffffffffa07c6450 [nvmet_rdma] #15 [ffff88084d3239b0] iw_conn_req_handler at ffffffffa0787480 [rdma_cm] #16 [ffff88084d323a60] cm_conn_req_handler at ffffffffa0775f06 [iw_cm] #17 [ffff88084d323ab0] process_event at ffffffffa0776019 [iw_cm] #18 [ffff88084d323af0] cm_work_handler at ffffffffa0776170 [iw_cm] #19 [ffff88084d323cb0] process_one_work at ffffffff810a1483 #20 [ffff88084d323d90] worker_thread at ffffffff810a211d #21 [ffff88084d323ec0] kthread at ffffffff810a6c5c #22 [ffff88084d323f50] ret_from_fork at ffffffff816e1ebf Fixes: 632bc3f ("IB/core, RDMA RW API: Do not exceed QP SGE send limit") Signed-off-by: Steve Wise <[email protected]> Reviewed-by: Bart Van Assche <[email protected]> Signed-off-by: Doug Ledford <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
dm0-
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Feb 13, 2017
commit 4dfce57 upstream. There have been several reports over the years of NULL pointer dereferences in xfs_trans_log_inode during xfs_fsr processes, when the process is doing an fput and tearing down extents on the temporary inode, something like: BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 PID: 29439 TASK: ffff880550584fa0 CPU: 6 COMMAND: "xfs_fsr" [exception RIP: xfs_trans_log_inode+0x10] #9 [ffff8800a57bbbe0] xfs_bunmapi at ffffffffa037398e [xfs] #10 [ffff8800a57bbce8] xfs_itruncate_extents at ffffffffa0391b29 [xfs] #11 [ffff8800a57bbd88] xfs_inactive_truncate at ffffffffa0391d0c [xfs] #12 [ffff8800a57bbdb8] xfs_inactive at ffffffffa0392508 [xfs] #13 [ffff8800a57bbdd8] xfs_fs_evict_inode at ffffffffa035907e [xfs] #14 [ffff8800a57bbe00] evict at ffffffff811e1b67 #15 [ffff8800a57bbe28] iput at ffffffff811e23a5 #16 [ffff8800a57bbe58] dentry_kill at ffffffff811dcfc8 #17 [ffff8800a57bbe88] dput at ffffffff811dd06c #18 [ffff8800a57bbea8] __fput at ffffffff811c823b #19 [ffff8800a57bbef0] ____fput at ffffffff811c846e #20 [ffff8800a57bbf00] task_work_run at ffffffff81093b27 #21 [ffff8800a57bbf30] do_notify_resume at ffffffff81013b0c #22 [ffff8800a57bbf50] int_signal at ffffffff8161405d As it turns out, this is because the i_itemp pointer, along with the d_ops pointer, has been overwritten with zeros when we tear down the extents during truncate. When the in-core inode fork on the temporary inode used by xfs_fsr was originally set up during the extent swap, we mistakenly looked at di_nextents to determine whether all extents fit inline, but this misses extents generated by speculative preallocation; we should be using if_bytes instead. This mistake corrupts the in-memory inode, and code in xfs_iext_remove_inline eventually gets bad inputs, causing it to memmove and memset incorrect ranges; this became apparent because the two values in ifp->if_u2.if_inline_ext[1] contained what should have been in d_ops and i_itemp; they were memmoved due to incorrect array indexing and then the original locations were zeroed with memset, again due to an array overrun. Fix this by properly using i_df.if_bytes to determine the number of extents, not di_nextents. Thanks to dchinner for looking at this with me and spotting the root cause. Signed-off-by: Eric Sandeen <[email protected]> Reviewed-by: Brian Foster <[email protected]> Signed-off-by: Dave Chinner <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
bgilbert
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Apr 12, 2017
[ Upstream commit 45caeaa ] As Eric Dumazet pointed out this also needs to be fixed in IPv6. v2: Contains the IPv6 tcp/Ipv6 dccp patches as well. We have seen a few incidents lately where a dst_enty has been freed with a dangling TCP socket reference (sk->sk_dst_cache) pointing to that dst_entry. If the conditions/timings are right a crash then ensues when the freed dst_entry is referenced later on. A Common crashing back trace is: #8 [] page_fault at ffffffff8163e648 [exception RIP: __tcp_ack_snd_check+74] . . #9 [] tcp_rcv_established at ffffffff81580b64 #10 [] tcp_v4_do_rcv at ffffffff8158b54a #11 [] tcp_v4_rcv at ffffffff8158cd02 #12 [] ip_local_deliver_finish at ffffffff815668f4 #13 [] ip_local_deliver at ffffffff81566bd9 #14 [] ip_rcv_finish at ffffffff8156656d #15 [] ip_rcv at ffffffff81566f06 #16 [] __netif_receive_skb_core at ffffffff8152b3a2 #17 [] __netif_receive_skb at ffffffff8152b608 #18 [] netif_receive_skb at ffffffff8152b690 #19 [] vmxnet3_rq_rx_complete at ffffffffa015eeaf [vmxnet3] #20 [] vmxnet3_poll_rx_only at ffffffffa015f32a [vmxnet3] #21 [] net_rx_action at ffffffff8152bac2 #22 [] __do_softirq at ffffffff81084b4f #23 [] call_softirq at ffffffff8164845c #24 [] do_softirq at ffffffff81016fc5 #25 [] irq_exit at ffffffff81084ee5 #26 [] do_IRQ at ffffffff81648ff8 Of course it may happen with other NIC drivers as well. It's found the freed dst_entry here: 224 static bool tcp_in_quickack_mode(struct sock *sk)↩ 225 {↩ 226 ▹ const struct inet_connection_sock *icsk = inet_csk(sk);↩ 227 ▹ const struct dst_entry *dst = __sk_dst_get(sk);↩ 228 ↩ 229 ▹ return (dst && dst_metric(dst, RTAX_QUICKACK)) ||↩ 230 ▹ ▹ (icsk->icsk_ack.quick && !icsk->icsk_ack.pingpong);↩ 231 }↩ But there are other backtraces attributed to the same freed dst_entry in netfilter code as well. All the vmcores showed 2 significant clues: - Remote hosts behind the default gateway had always been redirected to a different gateway. A rtable/dst_entry will be added for that host. Making more dst_entrys with lower reference counts. Making this more probable. - All vmcores showed a postitive LockDroppedIcmps value, e.g: LockDroppedIcmps 267 A closer look at the tcp_v4_err() handler revealed that do_redirect() will run regardless of whether user space has the socket locked. This can result in a race condition where the same dst_entry cached in sk->sk_dst_entry can be decremented twice for the same socket via: do_redirect()->__sk_dst_check()-> dst_release(). Which leads to the dst_entry being prematurely freed with another socket pointing to it via sk->sk_dst_cache and a subsequent crash. To fix this skip do_redirect() if usespace has the socket locked. Instead let the redirect take place later when user space does not have the socket locked. The dccp/IPv6 code is very similar in this respect, so fixing it there too. As Eric Garver pointed out the following commit now invalidates routes. Which can set the dst->obsolete flag so that ipv4_dst_check() returns null and triggers the dst_release(). Fixes: ceb3320 ("ipv4: Kill routes during PMTU/redirect updates.") Cc: Eric Garver <[email protected]> Cc: Hannes Sowa <[email protected]> Signed-off-by: Jon Maxwell <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
bgilbert
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Apr 24, 2017
[ Upstream commit 45caeaa ] As Eric Dumazet pointed out this also needs to be fixed in IPv6. v2: Contains the IPv6 tcp/Ipv6 dccp patches as well. We have seen a few incidents lately where a dst_enty has been freed with a dangling TCP socket reference (sk->sk_dst_cache) pointing to that dst_entry. If the conditions/timings are right a crash then ensues when the freed dst_entry is referenced later on. A Common crashing back trace is: #8 [] page_fault at ffffffff8163e648 [exception RIP: __tcp_ack_snd_check+74] . . #9 [] tcp_rcv_established at ffffffff81580b64 #10 [] tcp_v4_do_rcv at ffffffff8158b54a #11 [] tcp_v4_rcv at ffffffff8158cd02 #12 [] ip_local_deliver_finish at ffffffff815668f4 #13 [] ip_local_deliver at ffffffff81566bd9 #14 [] ip_rcv_finish at ffffffff8156656d #15 [] ip_rcv at ffffffff81566f06 #16 [] __netif_receive_skb_core at ffffffff8152b3a2 #17 [] __netif_receive_skb at ffffffff8152b608 #18 [] netif_receive_skb at ffffffff8152b690 #19 [] vmxnet3_rq_rx_complete at ffffffffa015eeaf [vmxnet3] #20 [] vmxnet3_poll_rx_only at ffffffffa015f32a [vmxnet3] #21 [] net_rx_action at ffffffff8152bac2 #22 [] __do_softirq at ffffffff81084b4f #23 [] call_softirq at ffffffff8164845c #24 [] do_softirq at ffffffff81016fc5 #25 [] irq_exit at ffffffff81084ee5 #26 [] do_IRQ at ffffffff81648ff8 Of course it may happen with other NIC drivers as well. It's found the freed dst_entry here: 224 static bool tcp_in_quickack_mode(struct sock *sk)↩ 225 {↩ 226 ▹ const struct inet_connection_sock *icsk = inet_csk(sk);↩ 227 ▹ const struct dst_entry *dst = __sk_dst_get(sk);↩ 228 ↩ 229 ▹ return (dst && dst_metric(dst, RTAX_QUICKACK)) ||↩ 230 ▹ ▹ (icsk->icsk_ack.quick && !icsk->icsk_ack.pingpong);↩ 231 }↩ But there are other backtraces attributed to the same freed dst_entry in netfilter code as well. All the vmcores showed 2 significant clues: - Remote hosts behind the default gateway had always been redirected to a different gateway. A rtable/dst_entry will be added for that host. Making more dst_entrys with lower reference counts. Making this more probable. - All vmcores showed a postitive LockDroppedIcmps value, e.g: LockDroppedIcmps 267 A closer look at the tcp_v4_err() handler revealed that do_redirect() will run regardless of whether user space has the socket locked. This can result in a race condition where the same dst_entry cached in sk->sk_dst_entry can be decremented twice for the same socket via: do_redirect()->__sk_dst_check()-> dst_release(). Which leads to the dst_entry being prematurely freed with another socket pointing to it via sk->sk_dst_cache and a subsequent crash. To fix this skip do_redirect() if usespace has the socket locked. Instead let the redirect take place later when user space does not have the socket locked. The dccp/IPv6 code is very similar in this respect, so fixing it there too. As Eric Garver pointed out the following commit now invalidates routes. Which can set the dst->obsolete flag so that ipv4_dst_check() returns null and triggers the dst_release(). Fixes: ceb3320 ("ipv4: Kill routes during PMTU/redirect updates.") Cc: Eric Garver <[email protected]> Cc: Hannes Sowa <[email protected]> Signed-off-by: Jon Maxwell <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
dm0-
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May 19, 2018
[ Upstream commit af50e4b ] syzbot caught an infinite recursion in nsh_gso_segment(). Problem here is that we need to make sure the NSH header is of reasonable length. BUG: MAX_LOCK_DEPTH too low! turning off the locking correctness validator. depth: 48 max: 48! 48 locks held by syz-executor0/10189: #0: (ptrval) (rcu_read_lock_bh){....}, at: __dev_queue_xmit+0x30f/0x34c0 net/core/dev.c:3517 #1: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #1: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #2: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #2: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #3: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #3: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #4: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #4: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #5: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #5: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #6: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #6: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #7: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #7: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #8: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #8: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #9: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #9: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #10: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #10: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #11: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #11: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #12: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #12: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #13: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #13: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #14: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #14: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #15: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #15: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #16: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #16: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #17: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #17: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #18: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #18: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #19: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #19: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #20: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #20: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #21: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #21: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #22: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #22: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #23: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #23: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #24: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #24: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #25: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #25: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #26: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #26: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #27: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #27: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #28: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #28: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #29: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #29: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #30: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #30: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #31: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #31: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 dccp_close: ABORT with 65423 bytes unread #32: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #32: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #33: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #33: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #34: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #34: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #35: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #35: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #36: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #36: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #37: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #37: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #38: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #38: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #39: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #39: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #40: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #40: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #41: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #41: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #42: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #42: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #43: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #43: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #44: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #44: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #45: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #45: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #46: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #46: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 #47: (ptrval) (rcu_read_lock){....}, at: __skb_pull include/linux/skbuff.h:2080 [inline] #47: (ptrval) (rcu_read_lock){....}, at: skb_mac_gso_segment+0x221/0x720 net/core/dev.c:2787 INFO: lockdep is turned off. CPU: 1 PID: 10189 Comm: syz-executor0 Not tainted 4.17.0-rc2+ #26 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 __lock_acquire+0x1788/0x5140 kernel/locking/lockdep.c:3449 lock_acquire+0x1dc/0x520 kernel/locking/lockdep.c:3920 rcu_lock_acquire include/linux/rcupdate.h:246 [inline] rcu_read_lock include/linux/rcupdate.h:632 [inline] skb_mac_gso_segment+0x25b/0x720 net/core/dev.c:2789 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 nsh_gso_segment+0x405/0xb60 net/nsh/nsh.c:107 skb_mac_gso_segment+0x3ad/0x720 net/core/dev.c:2792 __skb_gso_segment+0x3bb/0x870 net/core/dev.c:2865 skb_gso_segment include/linux/netdevice.h:4025 [inline] validate_xmit_skb+0x54d/0xd90 net/core/dev.c:3118 validate_xmit_skb_list+0xbf/0x120 net/core/dev.c:3168 sch_direct_xmit+0x354/0x11e0 net/sched/sch_generic.c:312 qdisc_restart net/sched/sch_generic.c:399 [inline] __qdisc_run+0x741/0x1af0 net/sched/sch_generic.c:410 __dev_xmit_skb net/core/dev.c:3243 [inline] __dev_queue_xmit+0x28ea/0x34c0 net/core/dev.c:3551 dev_queue_xmit+0x17/0x20 net/core/dev.c:3616 packet_snd net/packet/af_packet.c:2951 [inline] packet_sendmsg+0x40f8/0x6070 net/packet/af_packet.c:2976 sock_sendmsg_nosec net/socket.c:629 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:639 __sys_sendto+0x3d7/0x670 net/socket.c:1789 __do_sys_sendto net/socket.c:1801 [inline] __se_sys_sendto net/socket.c:1797 [inline] __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1797 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fixes: c411ed8 ("nsh: add GSO support") Signed-off-by: Eric Dumazet <[email protected]> Cc: Jiri Benc <[email protected]> Reported-by: syzbot <[email protected]> Acked-by: Jiri Benc <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
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[ Upstream commit fd3e71a ] conn_free() holds lock with spin_lock() and it is called by both nf_conncount_lookup() and nf_conncount_gc_list(). nf_conncount_lookup() is called from bottom-half context and nf_conncount_gc_list() from process context. So that spin_lock() call is not safe. Hence conn_free() should use spin_lock_bh() instead of spin_lock(). test commands: %nft add table ip filter %nft add chain ip filter input { type filter hook input priority 0\; } %nft add rule filter input meter test { ip saddr ct count over 2 } \ counter splat looks like: [ 461.996507] ================================ [ 461.998999] WARNING: inconsistent lock state [ 461.998999] 4.19.0-rc6+ #22 Not tainted [ 461.998999] -------------------------------- [ 461.998999] inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. [ 461.998999] kworker/0:2/134 [HC0[0]:SC0[0]:HE1:SE1] takes: [ 461.998999] 00000000a71a559a (&(&list->list_lock)->rlock){+.?.}, at: conn_free+0x69/0x2b0 [nf_conncount] [ 461.998999] {IN-SOFTIRQ-W} state was registered at: [ 461.998999] _raw_spin_lock+0x30/0x70 [ 461.998999] nf_conncount_add+0x28a/0x520 [nf_conncount] [ 461.998999] nft_connlimit_eval+0x401/0x580 [nft_connlimit] [ 461.998999] nft_dynset_eval+0x32b/0x590 [nf_tables] [ 461.998999] nft_do_chain+0x497/0x1430 [nf_tables] [ 461.998999] nft_do_chain_ipv4+0x255/0x330 [nf_tables] [ 461.998999] nf_hook_slow+0xb1/0x160 [ ... ] [ 461.998999] other info that might help us debug this: [ 461.998999] Possible unsafe locking scenario: [ 461.998999] [ 461.998999] CPU0 [ 461.998999] ---- [ 461.998999] lock(&(&list->list_lock)->rlock); [ 461.998999] <Interrupt> [ 461.998999] lock(&(&list->list_lock)->rlock); [ 461.998999] [ 461.998999] *** DEADLOCK *** [ 461.998999] [ ... ] Fixes: 5c789e1 ("netfilter: nf_conncount: Add list lock and gc worker, and RCU for init tree search") Signed-off-by: Taehee Yoo <[email protected]> Signed-off-by: Pablo Neira Ayuso <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
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Jan 7, 2019
[ Upstream commit 31568ec ] nf_conncount_tuple is an element of nft_connlimit and that is deleted by conn_free(). Elements can be deleted by both GC routine and data path functions (nf_conncount_lookup, nf_conncount_add) and they call conn_free() to free elements. But conn_free() only protects lists, not each element. So that list_del corruption could occurred. The conn_free() doesn't check whether element is already deleted. In order to protect elements, dead flag is added. If an element is deleted, dead flag is set. The only conn_free() can delete elements so that both list lock and dead flag are enough to protect it. test commands: %nft add table ip filter %nft add chain ip filter input { type filter hook input priority 0\; } %nft add rule filter input meter test { ip id ct count over 2 } counter splat looks like: [ 1779.495778] list_del corruption, ffff8800b6e12008->prev is LIST_POISON2 (dead000000000200) [ 1779.505453] ------------[ cut here ]------------ [ 1779.506260] kernel BUG at lib/list_debug.c:50! [ 1779.515831] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI [ 1779.516772] CPU: 0 PID: 33 Comm: kworker/0:2 Not tainted 4.19.0-rc6+ #22 [ 1779.516772] Workqueue: events_power_efficient nft_rhash_gc [nf_tables_set] [ 1779.516772] RIP: 0010:__list_del_entry_valid+0xd8/0x150 [ 1779.516772] Code: 39 48 83 c4 08 b8 01 00 00 00 5b 5d c3 48 89 ea 48 c7 c7 00 c3 5b 98 e8 0f dc 40 ff 0f 0b 48 c7 c7 60 c3 5b 98 e8 01 dc 40 ff <0f> 0b 48 c7 c7 c0 c3 5b 98 e8 f3 db 40 ff 0f 0b 48 c7 c7 20 c4 5b [ 1779.516772] RSP: 0018:ffff880119127420 EFLAGS: 00010286 [ 1779.516772] RAX: 000000000000004e RBX: dead000000000200 RCX: 0000000000000000 [ 1779.516772] RDX: 000000000000004e RSI: 0000000000000008 RDI: ffffed0023224e7a [ 1779.516772] RBP: ffff88011934bc10 R08: ffffed002367cea9 R09: ffffed002367cea9 [ 1779.516772] R10: 0000000000000001 R11: ffffed002367cea8 R12: ffff8800b6e12008 [ 1779.516772] R13: ffff8800b6e12010 R14: ffff88011934bc20 R15: ffff8800b6e12008 [ 1779.516772] FS: 0000000000000000(0000) GS:ffff88011b200000(0000) knlGS:0000000000000000 [ 1779.516772] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1779.516772] CR2: 00007fc876534010 CR3: 000000010da16000 CR4: 00000000001006f0 [ 1779.516772] Call Trace: [ 1779.516772] conn_free+0x9f/0x2b0 [nf_conncount] [ 1779.516772] ? nf_ct_tmpl_alloc+0x2a0/0x2a0 [nf_conntrack] [ 1779.516772] ? nf_conncount_add+0x520/0x520 [nf_conncount] [ 1779.516772] ? do_raw_spin_trylock+0x1a0/0x1a0 [ 1779.516772] ? do_raw_spin_trylock+0x10/0x1a0 [ 1779.516772] find_or_evict+0xe5/0x150 [nf_conncount] [ 1779.516772] nf_conncount_gc_list+0x162/0x360 [nf_conncount] [ 1779.516772] ? nf_conncount_lookup+0xee0/0xee0 [nf_conncount] [ 1779.516772] ? _raw_spin_unlock_irqrestore+0x45/0x50 [ 1779.516772] ? trace_hardirqs_off+0x6b/0x220 [ 1779.516772] ? trace_hardirqs_on_caller+0x220/0x220 [ 1779.516772] nft_rhash_gc+0x16b/0x540 [nf_tables_set] [ ... ] Fixes: 5c789e1 ("netfilter: nf_conncount: Add list lock and gc worker, and RCU for init tree search") Signed-off-by: Taehee Yoo <[email protected]> Signed-off-by: Pablo Neira Ayuso <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
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Sep 21, 2019
[ Upstream commit de166bb ] KASAN report this: kernel BUG at net/mac802154/main.c:130! invalid opcode: 0000 [#1] PREEMPT SMP CPU: 0 PID: 19932 Comm: modprobe Not tainted 5.1.0-rc6+ #22 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014 RIP: 0010:ieee802154_free_hw+0x2a/0x30 [mac802154] Code: 55 48 8d 57 38 48 89 e5 53 48 89 fb 48 8b 47 38 48 39 c2 75 15 48 8d 7f 48 e8 82 85 16 e1 48 8b 7b 28 e8 f9 ef 83 e2 5b 5d c3 <0f> 0b 0f 1f 40 00 55 48 89 e5 53 48 89 fb 0f b6 86 80 00 00 00 88 RSP: 0018:ffffc90001c7b9f0 EFLAGS: 00010206 RAX: ffff88822df3aa80 RBX: ffff88823143d5c0 RCX: 0000000000000002 RDX: ffff88823143d5f8 RSI: ffff88822b1fabc0 RDI: ffff88823143d5c0 RBP: ffffc90001c7b9f8 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: 0000000000000000 R12: 00000000fffffff4 R13: ffff88822dea4f50 R14: ffff88823143d7c0 R15: 00000000fffffff4 FS: 00007ff52e999540(0000) GS:ffff888237a00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fdc06dba768 CR3: 000000023160a000 CR4: 00000000000006f0 Call Trace: hwsim_add_one+0x2dd/0x540 [mac802154_hwsim] hwsim_probe+0x2f/0xb0 [mac802154_hwsim] platform_drv_probe+0x3a/0x90 ? driver_sysfs_add+0x79/0xb0 really_probe+0x1d4/0x2d0 driver_probe_device+0x50/0xf0 device_driver_attach+0x54/0x60 __driver_attach+0x7e/0xd0 ? device_driver_attach+0x60/0x60 bus_for_each_dev+0x68/0xc0 driver_attach+0x19/0x20 bus_add_driver+0x15e/0x200 driver_register+0x5b/0xf0 __platform_driver_register+0x31/0x40 hwsim_init_module+0x74/0x1000 [mac802154_hwsim] ? 0xffffffffa00e9000 do_one_initcall+0x6c/0x3cc ? kmem_cache_alloc_trace+0x248/0x3b0 do_init_module+0x5b/0x1f1 load_module+0x1db1/0x2690 ? m_show+0x1d0/0x1d0 __do_sys_finit_module+0xc5/0xd0 __x64_sys_finit_module+0x15/0x20 do_syscall_64+0x6b/0x1d0 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7ff52e4a2839 Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 1f f6 2c 00 f7 d8 64 89 01 48 RSP: 002b:00007ffffa7b3c08 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 RAX: ffffffffffffffda RBX: 00005647560a2a00 RCX: 00007ff52e4a2839 RDX: 0000000000000000 RSI: 00005647547f3c2e RDI: 0000000000000003 RBP: 00005647547f3c2e R08: 0000000000000000 R09: 00005647560a2a00 R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000 R13: 00005647560a2c10 R14: 0000000000040000 R15: 00005647560a2a00 Modules linked in: mac802154_hwsim(+) mac802154 [last unloaded: mac802154_hwsim] In hwsim_add_one, if hwsim_subscribe_all_others fails, we should call ieee802154_unregister_hw to free resources. Reported-by: Hulk Robot <[email protected]> Fixes: f25da51 ("ieee802154: hwsim: add replacement for fakelb") Signed-off-by: YueHaibing <[email protected]> Acked-by: Alexander Aring <[email protected]> Signed-off-by: Stefan Schmidt <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
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commit 68faa67 upstream. 'chrdev_open()' calls 'cdev_get()' to obtain a reference to the 'struct cdev *' stashed in the 'i_cdev' field of the target inode structure. If the pointer is NULL, then it is initialised lazily by looking up the kobject in the 'cdev_map' and so the whole procedure is protected by the 'cdev_lock' spinlock to serialise initialisation of the shared pointer. Unfortunately, it is possible for the initialising thread to fail *after* installing the new pointer, for example if the subsequent '->open()' call on the file fails. In this case, 'cdev_put()' is called, the reference count on the kobject is dropped and, if nobody else has taken a reference, the release function is called which finally clears 'inode->i_cdev' from 'cdev_purge()' before potentially freeing the object. The problem here is that a racing thread can happily take the 'cdev_lock' and see the non-NULL pointer in the inode, which can result in a refcount increment from zero and a warning: | ------------[ cut here ]------------ | refcount_t: addition on 0; use-after-free. | WARNING: CPU: 2 PID: 6385 at lib/refcount.c:25 refcount_warn_saturate+0x6d/0xf0 | Modules linked in: | CPU: 2 PID: 6385 Comm: repro Not tainted 5.5.0-rc2+ #22 | Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 | RIP: 0010:refcount_warn_saturate+0x6d/0xf0 | Code: 05 55 9a 15 01 01 e8 9d aa c8 ff 0f 0b c3 80 3d 45 9a 15 01 00 75 ce 48 c7 c7 00 9c 62 b3 c6 08 | RSP: 0018:ffffb524c1b9bc70 EFLAGS: 00010282 | RAX: 0000000000000000 RBX: ffff9e9da1f71390 RCX: 0000000000000000 | RDX: ffff9e9dbbd27618 RSI: ffff9e9dbbd18798 RDI: ffff9e9dbbd18798 | RBP: 0000000000000000 R08: 000000000000095f R09: 0000000000000039 | R10: 0000000000000000 R11: ffffb524c1b9bb20 R12: ffff9e9da1e8c700 | R13: ffffffffb25ee8b0 R14: 0000000000000000 R15: ffff9e9da1e8c700 | FS: 00007f3b87d26700(0000) GS:ffff9e9dbbd00000(0000) knlGS:0000000000000000 | CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 | CR2: 00007fc16909c000 CR3: 000000012df9c000 CR4: 00000000000006e0 | DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 | DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 | Call Trace: | kobject_get+0x5c/0x60 | cdev_get+0x2b/0x60 | chrdev_open+0x55/0x220 | ? cdev_put.part.3+0x20/0x20 | do_dentry_open+0x13a/0x390 | path_openat+0x2c8/0x1470 | do_filp_open+0x93/0x100 | ? selinux_file_ioctl+0x17f/0x220 | do_sys_open+0x186/0x220 | do_syscall_64+0x48/0x150 | entry_SYSCALL_64_after_hwframe+0x44/0xa9 | RIP: 0033:0x7f3b87efcd0e | Code: 89 54 24 08 e8 a3 f4 ff ff 8b 74 24 0c 48 8b 3c 24 41 89 c0 44 8b 54 24 08 b8 01 01 00 00 89 f4 | RSP: 002b:00007f3b87d259f0 EFLAGS: 00000293 ORIG_RAX: 0000000000000101 | RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f3b87efcd0e | RDX: 0000000000000000 RSI: 00007f3b87d25a80 RDI: 00000000ffffff9c | RBP: 00007f3b87d25e90 R08: 0000000000000000 R09: 0000000000000000 | R10: 0000000000000000 R11: 0000000000000293 R12: 00007ffe188f504e | R13: 00007ffe188f504f R14: 00007f3b87d26700 R15: 0000000000000000 | ---[ end trace 24f53ca58db8180a ]--- Since 'cdev_get()' can already fail to obtain a reference, simply move it over to use 'kobject_get_unless_zero()' instead of 'kobject_get()', which will cause the racing thread to return -ENXIO if the initialising thread fails unexpectedly. Cc: Hillf Danton <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Al Viro <[email protected]> Reported-by: [email protected] Signed-off-by: Will Deacon <[email protected]> Cc: stable <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]>
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This is an ancient bug that was actually attempted to be fixed once
(badly) by me eleven years ago in commit 4ceb5db ("Fix
get_user_pages() race for write access") but that was then undone due to
problems on s390 by commit f33ea7f ("fix get_user_pages bug").
In the meantime, the s390 situation has long been fixed, and we can now
fix it by checking the pte_dirty() bit properly (and do it better). The
s390 dirty bit was implemented in abf09be ("s390/mm: implement
software dirty bits") which made it into v3.9. Earlier kernels will
have to look at the page state itself.
Also, the VM has become more scalable, and what used a purely
theoretical race back then has become easier to trigger.
To fix it, we introduce a new internal FOLL_COW flag to mark the "yes,
we already did a COW" rather than play racy games with FOLL_WRITE that
is very fundamental, and then use the pte dirty flag to validate that
the FOLL_COW flag is still valid.
Reported-and-tested-by: Phil "not Paul" Oester [email protected]
Acked-by: Hugh Dickins [email protected]
Reviewed-by: Michal Hocko [email protected]
Cc: Andy Lutomirski [email protected]
Cc: Kees Cook [email protected]
Cc: Oleg Nesterov [email protected]
Cc: Willy Tarreau [email protected]
Cc: Nick Piggin [email protected]
Cc: Greg Thelen [email protected]
Cc: [email protected]
Signed-off-by: Linus Torvalds [email protected]