[ Upstream commit e58f5142f8 ]
When two UBLK_CMD_START_USER_RECOVERY commands are submitted, the
first one sets 'ubq->ubq_daemon' to NULL, and the second one triggers
WARN in ublk_queue_reinit() and subsequently a NULL pointer dereference
issue.
Fix it by adding the check in ublk_ctrl_start_recovery() and return
immediately in case of zero 'ub->nr_queues_ready'.
BUG: kernel NULL pointer dereference, address: 0000000000000028
RIP: 0010:ublk_ctrl_start_recovery.constprop.0+0x82/0x180
Call Trace:
<TASK>
? __die+0x20/0x70
? page_fault_oops+0x75/0x170
? exc_page_fault+0x64/0x140
? asm_exc_page_fault+0x22/0x30
? ublk_ctrl_start_recovery.constprop.0+0x82/0x180
ublk_ctrl_uring_cmd+0x4f7/0x6c0
? pick_next_task_idle+0x26/0x40
io_uring_cmd+0x9a/0x1b0
io_issue_sqe+0x193/0x3f0
io_wq_submit_work+0x9b/0x390
io_worker_handle_work+0x165/0x360
io_wq_worker+0xcb/0x2f0
? finish_task_switch.isra.0+0x203/0x290
? finish_task_switch.isra.0+0x203/0x290
? __pfx_io_wq_worker+0x10/0x10
ret_from_fork+0x2d/0x50
? __pfx_io_wq_worker+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
Fixes: c732a852b4 ("ublk_drv: add START_USER_RECOVERY and END_USER_RECOVERY support")
Reported-and-tested-by: Changhui Zhong <czhong@redhat.com>
Closes: https://lore.kernel.org/all/CAGVVp+UvLiS+bhNXV-h2icwX1dyybbYHeQUuH7RYqUvMQf6N3w@mail.gmail.com
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Li Nan <linan122@huawei.com>
Link: https://lore.kernel.org/r/20240904031348.4139545-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
ca24943589