Skip to content

Commit

Permalink
Revert "media: dvb-core: Fix use-after-free on race condition at dvb_…
Browse files Browse the repository at this point in the history 
…frontend"

As reported by Thomas Voegtle <[email protected]>, sometimes a DVB card does
not initialize properly booting Linux 6.4-rc4. This is not always, maybe
in 3 out of 4 attempts.

After double-checking, the root cause seems to be related to the
UAF fix, which is causing a race issue:

[   26.332149] tda10071 7-0005: found a 'NXP TDA10071' in cold state, will try to load a firmware
[   26.340779] tda10071 7-0005: downloading firmware from file 'dvb-fe-tda10071.fw'
[  989.277402] INFO: task vdr:743 blocked for more than 491 seconds.
[  989.283504]       Not tainted 6.4.0-rc5-i5 #249
[  989.288036] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  989.295860] task:vdr             state:D stack:0     pid:743   ppid:711    flags:0x00004002
[  989.295865] Call Trace:
[  989.295867]  <TASK>
[  989.295869]  __schedule+0x2ea/0x12d0
[  989.295877]  ? asm_sysvec_apic_timer_interrupt+0x16/0x20
[  989.295881]  schedule+0x57/0xc0
[  989.295884]  schedule_preempt_disabled+0xc/0x20
[  989.295887]  __mutex_lock.isra.16+0x237/0x480
[  989.295891]  ? dvb_get_property.isra.10+0x1bc/0xa50
[  989.295898]  ? dvb_frontend_stop+0x36/0x180
[  989.338777]  dvb_frontend_stop+0x36/0x180
[  989.338781]  dvb_frontend_open+0x2f1/0x470
[  989.338784]  dvb_device_open+0x81/0xf0
[  989.338804]  ? exact_lock+0x20/0x20
[  989.338808]  chrdev_open+0x7f/0x1c0
[  989.338811]  ? generic_permission+0x1a2/0x230
[  989.338813]  ? link_path_walk.part.63+0x340/0x380
[  989.338815]  ? exact_lock+0x20/0x20
[  989.338817]  do_dentry_open+0x18e/0x450
[  989.374030]  path_openat+0xca5/0xe00
[  989.374031]  ? terminate_walk+0xec/0x100
[  989.374034]  ? path_lookupat+0x93/0x140
[  989.374036]  do_filp_open+0xc0/0x140
[  989.374038]  ? __call_rcu_common.constprop.91+0x92/0x240
[  989.374041]  ? __check_object_size+0x147/0x260
[  989.374043]  ? __check_object_size+0x147/0x260
[  989.374045]  ? alloc_fd+0xbb/0x180
[  989.374048]  ? do_sys_openat2+0x243/0x310
[  989.374050]  do_sys_openat2+0x243/0x310
[  989.374052]  do_sys_open+0x52/0x80
[  989.374055]  do_syscall_64+0x5b/0x80
[  989.421335]  ? __task_pid_nr_ns+0x92/0xa0
[  989.421337]  ? syscall_exit_to_user_mode+0x20/0x40
[  989.421339]  ? do_syscall_64+0x67/0x80
[  989.421341]  ? syscall_exit_to_user_mode+0x20/0x40
[  989.421343]  ? do_syscall_64+0x67/0x80
[  989.421345]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[  989.421348] RIP: 0033:0x7fe895d067e3
[  989.421349] RSP: 002b:00007fff933c2ba0 EFLAGS: 00000293 ORIG_RAX: 0000000000000101
[  989.421351] RAX: ffffffffffffffda RBX: 00007fff933c2c10 RCX: 00007fe895d067e3
[  989.421352] RDX: 0000000000000802 RSI: 00005594acdce160 RDI: 00000000ffffff9c
[  989.421353] RBP: 0000000000000802 R08: 0000000000000000 R09: 0000000000000000
[  989.421353] R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
[  989.421354] R13: 00007fff933c2ca0 R14: 00000000ffffffff R15: 00007fff933c2c90
[  989.421355]  </TASK>

This reverts commit 6769a0b.

Fixes: 6769a0b ("media: dvb-core: Fix use-after-free on race condition at dvb_frontend")
Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Mauro Carvalho Chehab <[email protected]>
  • Loading branch information
@mchehab
mchehab committed Jun 14, 2023
1 parent 4b0a501 commit ec21a38
Show file tree
Hide file tree
Showing 2 changed files with 10 additions and 49 deletions.
53 changes: 9 additions & 44 deletions drivers/media/dvb-core/dvb_frontend.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -817,26 +817,15 @@ static void dvb_frontend_stop(struct dvb_frontend *fe)

dev_dbg(fe->dvb->device, "%s:\n", __func__);

mutex_lock(&fe->remove_mutex);

if (fe->exit != DVB_FE_DEVICE_REMOVED)
fe->exit = DVB_FE_NORMAL_EXIT;
mb();

if (!fepriv->thread) {
mutex_unlock(&fe->remove_mutex);
if (!fepriv->thread)
return;
}

kthread_stop(fepriv->thread);

mutex_unlock(&fe->remove_mutex);

if (fepriv->dvbdev->users < -1) {
wait_event(fepriv->dvbdev->wait_queue,
fepriv->dvbdev->users == -1);
}

sema_init(&fepriv->sem, 1);
fepriv->state = FESTATE_IDLE;

Expand Down Expand Up @@ -2780,22 +2769,17 @@ static int dvb_frontend_open(struct inode *inode, struct file *file)
struct dvb_adapter *adapter = fe->dvb;
int ret;

mutex_lock(&fe->remove_mutex);

dev_dbg(fe->dvb->device, "%s:\n", __func__);
if (fe->exit == DVB_FE_DEVICE_REMOVED) {
ret = -ENODEV;
goto err_remove_mutex;
}
if (fe->exit == DVB_FE_DEVICE_REMOVED)
return -ENODEV;

if (adapter->mfe_shared == 2) {
mutex_lock(&adapter->mfe_lock);
if ((file->f_flags & O_ACCMODE) != O_RDONLY) {
if (adapter->mfe_dvbdev &&
!adapter->mfe_dvbdev->writers) {
mutex_unlock(&adapter->mfe_lock);
ret = -EBUSY;
goto err_remove_mutex;
return -EBUSY;
}
adapter->mfe_dvbdev = dvbdev;
}
Expand All @@ -2818,10 +2802,8 @@ static int dvb_frontend_open(struct inode *inode, struct file *file)
while (mferetry-- && (mfedev->users != -1 ||
mfepriv->thread)) {
if (msleep_interruptible(500)) {
if (signal_pending(current)) {
ret = -EINTR;
goto err_remove_mutex;
}
if (signal_pending(current))
return -EINTR;
}
}

Expand All @@ -2833,8 +2815,7 @@ static int dvb_frontend_open(struct inode *inode, struct file *file)
if (mfedev->users != -1 ||
mfepriv->thread) {
mutex_unlock(&adapter->mfe_lock);
ret = -EBUSY;
goto err_remove_mutex;
return -EBUSY;
}
adapter->mfe_dvbdev = dvbdev;
}
Expand Down Expand Up @@ -2893,8 +2874,6 @@ static int dvb_frontend_open(struct inode *inode, struct file *file)

if (adapter->mfe_shared)
mutex_unlock(&adapter->mfe_lock);

mutex_unlock(&fe->remove_mutex);
return ret;

err3:
Expand All @@ -2916,9 +2895,6 @@ static int dvb_frontend_open(struct inode *inode, struct file *file)
err0:
if (adapter->mfe_shared)
mutex_unlock(&adapter->mfe_lock);

err_remove_mutex:
mutex_unlock(&fe->remove_mutex);
return ret;
}

Expand All @@ -2929,8 +2905,6 @@ static int dvb_frontend_release(struct inode *inode, struct file *file)
struct dvb_frontend_private *fepriv = fe->frontend_priv;
int ret;

mutex_lock(&fe->remove_mutex);

dev_dbg(fe->dvb->device, "%s:\n", __func__);

if ((file->f_flags & O_ACCMODE) != O_RDONLY) {
Expand All @@ -2952,18 +2926,10 @@ static int dvb_frontend_release(struct inode *inode, struct file *file)
}
mutex_unlock(&fe->dvb->mdev_lock);
#endif
if (fe->exit != DVB_FE_NO_EXIT)
wake_up(&dvbdev->wait_queue);
if (fe->ops.ts_bus_ctrl)
fe->ops.ts_bus_ctrl(fe, 0);

if (fe->exit != DVB_FE_NO_EXIT) {
mutex_unlock(&fe->remove_mutex);
wake_up(&dvbdev->wait_queue);
} else {
mutex_unlock(&fe->remove_mutex);
}

} else {
mutex_unlock(&fe->remove_mutex);
}

dvb_frontend_put(fe);
Expand Down Expand Up @@ -3064,7 +3030,6 @@ int dvb_register_frontend(struct dvb_adapter *dvb,
fepriv = fe->frontend_priv;

kref_init(&fe->refcount);
mutex_init(&fe->remove_mutex);

/*
* After initialization, there need to be two references: one
Expand Down
6 changes: 1 addition & 5 deletions include/media/dvb_frontend.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -686,10 +686,7 @@ struct dtv_frontend_properties {
* @id: Frontend ID
* @exit: Used to inform the DVB core that the frontend
* thread should exit (usually, means that the hardware
* got disconnected).
* @remove_mutex: mutex that avoids a race condition between a callback
* called when the hardware is disconnected and the
* file_operations of dvb_frontend.
* got disconnected.
*/

struct dvb_frontend {
Expand All @@ -707,7 +704,6 @@ struct dvb_frontend {
int (*callback)(void *adapter_priv, int component, int cmd, int arg);
int id;
unsigned int exit;
struct mutex remove_mutex;
};

/**
Expand Down

0 comments on commit ec21a38

Please sign in to comment.