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ublk_drv: fix NULL pointer dereference in ublk_ctrl_start_recovery()
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BugLink: https://bugs.launchpad.net/bugs/2085849

[ Upstream commit e58f514 ]

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: c732a85 ("ublk_drv: add START_USER_RECOVERY and END_USER_RECOVERY support")
Reported-and-tested-by: Changhui Zhong <[email protected]>
Closes: https://lore.kernel.org/all/CAGVVp+UvLiS+bhNXV-h2icwX1dyybbYHeQUuH7RYqUvMQf6N3w@mail.gmail.com
Reviewed-by: Ming Lei <[email protected]>
Signed-off-by: Li Nan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
CVE-2024-46735
Signed-off-by: Manuel Diewald <[email protected]>
Signed-off-by: Roxana Nicolescu <[email protected]>
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@mehmetb0
Li Nan authored and mehmetb0 committed Nov 9, 2024
1 parent 5ad527b commit febac31
Showing 1 changed file with 2 additions and 0 deletions.
2 changes: 2 additions & 0 deletions drivers/block/ublk_drv.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2666,6 +2666,8 @@ static int ublk_ctrl_start_recovery(struct ublk_device *ub,
mutex_lock(&ub->mutex);
if (!ublk_can_use_recovery(ub))
goto out_unlock;
if (!ub->nr_queues_ready)
goto out_unlock;
/*
* START_RECOVERY is only allowd after:
*
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