bcachefs: return err ptr instead of null in read sb clean

syzbot reported a null-ptr-deref in bch2_fs_start. [0] When a sb is marked clear but doesn't have a clean section bch2_read_superblock_clean returns NULL which PTR_ERR_OR_ZERO lets through, eventually leading to a null ptr dereference down the line. Adjust read sb clean to return an ERR_PTR indicating the invalid clean section. [0] https://syzkaller.appspot.com/bug?extid=1cecc37d87c4286e5543 Reported-by: [email protected] Closes: https://syzkaller.appspot.com/bug?extid=1cecc37d87c4286e5543 Signed-off-by: Diogo Jahchan Koike <[email protected]> Signed-off-by: Kent Overstreet <[email protected]>
koverstreet · Sep 10, 2024 · b72bcc9 · b72bcc9
1 parent 5cf488d
commit b72bcc9
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/fs/bcachefs/sb-clean.c b/fs/bcachefs/sb-clean.c
@@ -155,7 +155,7 @@ struct bch_sb_field_clean *bch2_read_superblock_clean(struct bch_fs *c)
 		SET_BCH_SB_CLEAN(c->disk_sb.sb, false);
 		c->sb.clean = false;
 		mutex_unlock(&c->sb_lock);
-		return NULL;
+		return ERR_PTR(-BCH_ERR_invalid_sb_clean);
 	}
 
 	clean = kmemdup(sb_clean, vstruct_bytes(&sb_clean->field),