]> git.baikalelectronics.ru Git - kernel.git/commit
btrfs: fix null pointer deref when target device is missing
authorAnand Jain <anand.jain@oracle.com>
Sat, 24 Feb 2018 11:43:56 +0000 (19:43 +0800)
committerDavid Sterba <dsterba@suse.com>
Mon, 26 Mar 2018 13:09:34 +0000 (15:09 +0200)
commitb72f8b1a8d236241aebba051ee8b75962548a900
tree4f6374052f8dab9a9b800e6c37b506d519627d2f
parentad348f5cd6202dd83c9c18b3ca48754dc0370536
btrfs: fix null pointer deref when target device is missing

The replace target device can be missing when mounted with -o degraded,
but we wont allocate a missing btrfs_device to it. So check the device
before accessing.

BUG: unable to handle kernel NULL pointer dereference at 00000000000000b0
IP: btrfs_destroy_dev_replace_tgtdev+0x43/0xf0 [btrfs]
Call Trace:
btrfs_dev_replace_cancel+0x15f/0x180 [btrfs]
btrfs_ioctl+0x2216/0x2590 [btrfs]
do_vfs_ioctl+0x625/0x650
SyS_ioctl+0x4e/0x80
do_syscall_64+0x5d/0x160
entry_SYSCALL64_slow_path+0x25/0x25

This patch has been moved in front of patch "btrfs: log, when replace,
is canceled by the user" that could reproduce the crash if the system
reboots inside btrfs_dev_replace_start before the
btrfs_dev_replace_finishing call.

 $ mkfs /dev/sda
 $ mount /dev/sda mnt
 $ btrfs replace start /dev/sda /dev/sdb
 <insert reboot>
 $ mount po degraded /dev/sdb mnt
 <crash>

Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ added reproducer description from mail ]
Signed-off-by: David Sterba <dsterba@suse.com>
fs/btrfs/dev-replace.c