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ptp: ocp: fix use-after-free bugs causing by ptp_ocp_watchdog

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[ Upstream commit 8bf935cf789872350b04c1a6468b0a509f67afb2 ]

The ptp_ocp_detach() only shuts down the watchdog timer if it is
pending. However, if the timer handler is already running, the
timer_delete_sync() is not called. This leads to race conditions
where the devlink that contains the ptp_ocp is deallocated while
the timer handler is still accessing it, resulting in use-after-free
bugs. The following details one of the race scenarios.

(thread 1)                           | (thread 2)
ptp_ocp_remove()                     |
  ptp_ocp_detach()                   | ptp_ocp_watchdog()
    if (timer_pending(&bp->watchdog))|   bp = timer_container_of()
      timer_delete_sync()            |
                                     |
  devlink_free(devlink) //free       |
                                     |   bp-> //use

Resolve this by unconditionally calling timer_delete_sync() to ensure
the timer is reliably deactivated, preventing any access after free.

Fixes: 773bda9649 ("ptp: ocp: Expose various resources on the timecard.")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://patch.msgid.link/20250828082949.28189-1-duoming@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Duoming Zhou 2025-08-28 16:29:49 +08:00 committed by Greg Kroah-Hartman
parent 07edb77630
commit f10d3c7267
1 changed files with 1 additions and 2 deletions
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3
drivers/ptp/ptp_ocp.c
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@ -4557,8 +4557,7 @@ ptp_ocp_detach(struct ptp_ocp *bp)
ptp_ocp_debugfs_remove_device(bp);
ptp_ocp_detach_sysfs(bp);
ptp_ocp_attr_group_del(bp);
if (timer_pending(&bp->watchdog))
timer_delete_sync(&bp->watchdog);
timer_delete_sync(&bp->watchdog);
if (bp->ts0)
ptp_ocp_unregister_ext(bp->ts0);
if (bp->ts1)