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linux/drivers/block
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Bob Liu 7602843fd8 block: null_blk: fix race condition for null_del_dev 
Dulicate call of null_del_dev() will trigger null pointer error like below.
The reason is a race condition between nullb_device_power_store() and
nullb_group_drop_item().

  CPU#0                         CPU#1
  ----------------              -----------------
  do_rmdir()
   >configfs_rmdir()
    >client_drop_item()
     >nullb_group_drop_item()
                                nullb_device_power_store()
				>null_del_dev()

      >test_and_clear_bit(NULLB_DEV_FL_UP
       >null_del_dev()
       ^^^^^
       Duplicated null_dev_dev() triger null pointer error

				>clear_bit(NULLB_DEV_FL_UP

The fix could be keep the sequnce of clear NULLB_DEV_FL_UP and null_del_dev().

[  698.613600] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
[  698.613608] #PF error: [normal kernel read fault]
[  698.613611] PGD 0 P4D 0
[  698.613619] Oops: 0000 [#1] SMP PTI
[  698.613627] CPU: 3 PID: 6382 Comm: rmdir Not tainted 5.0.0+ #35
[  698.613631] Hardware name: LENOVO 20LJS2EV08/20LJS2EV08, BIOS R0SET33W (1.17 ) 07/18/2018
[  698.613644] RIP: 0010:null_del_dev+0xc/0x110 [null_blk]
[  698.613649] Code: 00 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 0b eb 97 e8 47 bb 2a e8 0f 1f 80 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41 54 53 <8b> 77 18 48 89 fb 4c 8b 27 48 c7 c7 40 57 1e c1 e8 bf c7 cb e8 48
[  698.613654] RSP: 0018:ffffb887888bfde0 EFLAGS: 00010286
[  698.613659] RAX: 0000000000000000 RBX: ffff9d436d92bc00 RCX: ffff9d43a9184681
[  698.613663] RDX: ffffffffc11e5c30 RSI: 0000000068be6540 RDI: 0000000000000000
[  698.613667] RBP: ffffb887888bfdf0 R08: 0000000000000001 R09: 0000000000000000
[  698.613671] R10: ffffb887888bfdd8 R11: 0000000000000f16 R12: ffff9d436d92bc08
[  698.613675] R13: ffff9d436d94e630 R14: ffffffffc11e5088 R15: ffffffffc11e5000
[  698.613680] FS:  00007faa68be6540(0000) GS:ffff9d43d14c0000(0000) knlGS:0000000000000000
[  698.613685] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  698.613689] CR2: 0000000000000018 CR3: 000000042f70c002 CR4: 00000000003606e0
[  698.613693] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  698.613697] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  698.613700] Call Trace:
[  698.613712]  nullb_group_drop_item+0x50/0x70 [null_blk]
[  698.613722]  client_drop_item+0x29/0x40
[  698.613728]  configfs_rmdir+0x1ed/0x300
[  698.613738]  vfs_rmdir+0xb2/0x130
[  698.613743]  do_rmdir+0x1c7/0x1e0
[  698.613750]  __x64_sys_rmdir+0x17/0x20
[  698.613759]  do_syscall_64+0x5a/0x110
[  698.613768]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-15 01:43:48 -06:00
..
aoe block: aoe: no need to check return value of debugfs_create functions 2019-06-04 13:38:23 -06:00
drbd treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 91 2019-05-24 17:37:53 +02:00
mtip32xx mtip32xx: also set max_segment_size in the device 2019-06-05 13:18:39 -06:00
paride Linux 5.1-rc6 2019-04-22 09:47:36 -06:00
rsxx rsxx: don't call dma_set_max_seg_size 2019-06-05 13:18:39 -06:00
xen-blkback treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157 2019-05-30 11:26:37 -07:00
zram treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
amiflop.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
ataflop.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
brd.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
cryptoloop.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 30 2019-05-24 17:27:10 +02:00
floppy.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
Kconfig drivers/block: Remove DAC960 driver 2018-10-17 09:42:30 -06:00
loop.c loop: Don't change loop device under exclusive opener 2019-05-27 07:34:04 -06:00
loop.h block/loop: Use global lock for ioctl() operation. 2018-11-08 06:30:11 -07:00
Makefile drivers/block: Remove DAC960 driver 2018-10-17 09:42:30 -06:00
nbd.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 127 2019-05-30 11:25:13 -07:00
null_blk.h null_blk: add zoned config support information 2019-01-06 10:58:27 -07:00
null_blk_main.c block: null_blk: fix race condition for null_del_dev 2019-06-15 01:43:48 -06:00
null_blk_zoned.c null_blk: remove duplicate check for report zone 2019-06-13 03:00:30 -06:00
pktcdvd.c block: genhd: remove async_events field 2019-04-12 13:35:22 -06:00
ps3disk.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 164 2019-05-30 11:26:38 -07:00
ps3vram.c block/ps3vram: Use %llu to format sector_t after LBDAF removal 2019-06-13 03:17:50 -06:00
rbd.c rbd: don't assert on writes to snapshots 2019-05-07 19:43:04 +02:00
rbd_types.h
skd_main.c block: kill BLK_MQ_F_SG_MERGE 2019-02-15 08:40:12 -07:00
skd_s1120.h skd: Use __packed only when needed 2017-08-18 08:45:29 -06:00
sunvdc.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
swim.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
swim3.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
swim_asm.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sx8.c sx8: use a per-host tag_set 2018-11-09 08:14:14 -07:00
umem.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 349 2019-06-05 17:37:08 +02:00
umem.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 348 2019-06-05 17:37:08 +02:00
virtio_blk.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
xen-blkfront.c xen-blkfront: switch kcalloc to kvcalloc for large array allocation 2019-06-03 22:16:19 -04:00
xsysace.c Linux 5.1-rc6 2019-04-22 09:47:36 -06:00
z2ram.c powerpc updates for 4.20 2018-10-26 14:36:21 -07:00