loop: Do not call loop_unplug for not configured loop device.
PATCH 1/1 loop: Do not call loop_unplug for not configured loop device.
Do not call loop_unplug for not configured loop device.
In loop_unplug() function is expected that mapping is set and lo->lo_backing_file is not NULL.
Unfortunately loop_set_fd() set the request queue unplug function, but loop_clr_fd() doesn't clear that.
Loop device allows open of non-configured loop in some situations. If the unplug on request queue is called, loop module oopses because of missing lo_backing_file.
Simple reproducer:
losetup /dev/loop0 /xxx
losetup -d /dev/loop0
dmsetup create x --table "0 1 linear /dev/loop0 0"
EIP is at loop_unplug+0x1d/0x3b
...
Call Trace: blk_unplug+0x57/0x5e dm_table_unplug_all+0x34/0x77 [dm_mod] destroy_inode+0x27/0x38 generic_delete_inode+0xd5/0xd9 iput+0x4b/0x4e dm_resume+0xca/0xfe [dm_mod] dev_suspend+0x143/0x165 [dm_mod] dm_ctl_ioctl+0x18e/0x1cf [dm_mod] dev_suspend+0x0/0x165 [dm_mod] dm_ctl_ioctl+0x0/0x1cf [dm_mod] vfs_ioctl+0x22/0x69 do_vfs_ioctl+0x39d/0x3c7 trace_hardirqs_on+0xb/0xd remove_vma+0x50/0x56 do_munmap+0x21c/0x237 sys_ioctl+0x2c/0x45 sysenter_do_call+0x12/0x31
Several reports here
http://www.kerneloops.org/search.php?search=loop_unplug
Fix it by simply clear unplug function together with removing of backing file.
--- drivers/block/loop.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)
drivers/block/loop.c +1 -0
@@ -919,6 +919,7 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)kthread_stop (lo->lo_thread); + lo->lo_queue->unplug_fn =NULL ; lo->lo_backing_file =NULL ;loop_release_xfer (lo);
Jens Axboe
AppliedQuoted 56 lines · Milan Broz
Do not call
loop_unplugfor not configured loop device.In
loop_unplug()function is expected that mapping is set andlo->lo_backing_fileis not NULL.Unfortunately
loop_set_fd()set the request queue unplug function, butloop_clr_fd()doesn't clear that.Loop device allows open of non-configured loop in some situations. If the unplug on request queue is called, loop module oopses because of missing
lo_backing_file.Simple reproducer:
losetup/dev/loop0/xxx
losetup -d/dev/loop0
dmsetup create x --table "0 1 linear/dev/loop00"EIP is at
loop_unplug+0x1d/0x3b
...Call Trace: blk_unplug+0x57/0x5e dm_table_unplug_all+0x34/0x77 [dm_mod] destroy_inode+0x27/0x38 generic_delete_inode+0xd5/0xd9 iput+0x4b/0x4e dm_resume+0xca/0xfe [dm_mod] dev_suspend+0x143/0x165 [dm_mod] dm_ctl_ioctl+0x18e/0x1cf [dm_mod] dev_suspend+0x0/0x165 [dm_mod] dm_ctl_ioctl+0x0/0x1cf [dm_mod] vfs_ioctl+0x22/0x69 do_vfs_ioctl+0x39d/0x3c7 trace_hardirqs_on+0xb/0xd remove_vma+0x50/0x56 do_munmap+0x21c/0x237 sys_ioctl+0x2c/0x45 sysenter_do_call+0x12/0x31Several reports here
http://www.kerneloops.org/search.php?search=loop_unplugFix it by simply clear unplug function together with removing of backing file.
Signed-off-by Milan Broz <[email protected]>--- drivers/block/loop.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)drivers/block/loop.c +0
-0
drivers/block/loop.c static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev) · line 925
Quoted 7 lines
drivers/block/loop.c +1
-0@@ -919,6 +919,7 @@ static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)kthread_stop (lo->lo_thread); + lo->lo_queue->unplug_fn =NULL ; lo->lo_backing_file =NULL ;loop_release_xfer (lo);
Thanks, applied.
Signature · 1 line
Jens Axboe