block: fix crash in 'blk_mq_elv_switch_none'
Syzbot found the following issue:
general protection fault, probably for non-canonical address 0xdffffc000000001d: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000000e8-0x00000000000000ef]
CPU: 0 PID: 5234 Comm: syz-executor931 Not tainted 6.1.0-rc3-next-
20221102-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
RIP: 0010:__elevator_get block/elevator.h:94 [inline]
RIP: 0010:blk_mq_elv_switch_none block/blk-mq.c:4593 [inline]
RIP: 0010:__blk_mq_update_nr_hw_queues block/blk-mq.c:4658 [inline]
RIP: 0010:blk_mq_update_nr_hw_queues+0x304/0xe40 block/blk-mq.c:4709
RSP: 0018:
ffffc90003cdfc08 EFLAGS:
00010206
RAX:
0000000000000000 RBX:
dffffc0000000000 RCX:
0000000000000000
RDX:
000000000000001d RSI:
0000000000000002 RDI:
00000000000000e8
RBP:
ffff88801dbd0000 R08:
ffff888027c89398 R09:
ffffffff8de2e517
R10:
fffffbfff1bc5ca2 R11:
0000000000000000 R12:
ffffc90003cdfc70
R13:
ffff88801dbd0008 R14:
ffff88801dbd03f8 R15:
ffff888027c89380
FS:
0000555557259300(0000) GS:
ffff8880b9a00000(0000) knlGS:
0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0:
0000000080050033
CR2:
00000000005d84c8 CR3:
000000007a7cb000 CR4:
00000000003506f0
DR0:
0000000000000000 DR1:
0000000000000000 DR2:
0000000000000000
DR3:
0000000000000000 DR6:
00000000fffe0ff0 DR7:
0000000000000400
Call Trace:
<TASK>
nbd_start_device+0x153/0xc30 drivers/block/nbd.c:1355
nbd_start_device_ioctl drivers/block/nbd.c:1405 [inline]
__nbd_ioctl drivers/block/nbd.c:1481 [inline]
nbd_ioctl+0x5a1/0xbd0 drivers/block/nbd.c:1521
blkdev_ioctl+0x36e/0x800 block/ioctl.c:614
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
As after
dd6f7f17bf58 commit move '__elevator_get(qe->type)' before set
'qe->type', so will lead to access wild pointer.
To solve above issue get 'qe->type' after set 'qe->type'.
Reported-by: syzbot+746a4eece09f86bc39d7@syzkaller.appspotmail.com
Fixes:
dd6f7f17bf58("block: add proper helpers for elevator_type module refcount management")
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221107033956.3276891-1-yebin@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>