Re: [PATCH] perf/core: Close owner-list publication race with remove-on-exec

[sashiko-bot@kernel.org]

> perf_event_open() makes a user event visible in the target context before
> adding owner_entry to the opener's perf_event_list.  For a remote task, it
> also releases exec_update_lock before adding the list node.
> 
> A concurrent target exec can therefore process a remove_on_exec event in
> this interval.  perf_remove_from_owner() sees the published non-NULL owner
> and calls list_del_init() on the zero-allocated, but not initialized,
> owner_entry.  DEBUG_LIST reports a NULL-link list corruption and can panic
> the kernel.
> 
> If list corruption reporting is non-fatal, list_del_init() initializes the
> node and clears the owner.  The open path then adds the ownerless event to
> the opener's list.  Closing the returned file descriptor frees the event
> while it remains linked, and the next owner-list insertion accesses the
> freed object.
> [ ... ]
> 
> Fixes: 2e498d0a74e5 ("perf: Add support for event removal on exec")
> Cc: stable@vger.kernel.org
> Assisted-by: LLM
> Signed-off-by: Daehyeon Ko <4ncienth@gmail.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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