6.16-stable review patch. If anyone has any objections, please let me know.
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From: Duoming Zhou duoming@zju.edu.cn
[ 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: 773bda964921 ("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 --- drivers/ptp/ptp_ocp.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c index 1e7f72e575576..5388285475952 100644 --- a/drivers/ptp/ptp_ocp.c +++ b/drivers/ptp/ptp_ocp.c @@ -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)