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rcu: Return early if callback is not specified

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[ Upstream commit 33b6a1f155 ]

Currently the call_rcu() API does not check whether a callback
pointer is NULL. If NULL is passed, rcu_core() will try to invoke
it, resulting in NULL pointer dereference and a kernel crash.

To prevent this and improve debuggability, this patch adds a check
for NULL and emits a kernel stack trace to help identify a faulty
caller.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Uladzislau Rezki (Sony) 2025-06-10 19:34:48 +02:00 committed by Greg Kroah-Hartman
parent f994086704
commit 100040bff2
1 changed files with 4 additions and 0 deletions
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4
kernel/rcu/tree.c
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@ -2827,6 +2827,10 @@ void call_rcu(struct rcu_head *head, rcu_callback_t func)
/* Misaligned rcu_head! */ /* Misaligned rcu_head! */
WARN_ON_ONCE((unsigned long)head & (sizeof(void *) - 1)); WARN_ON_ONCE((unsigned long)head & (sizeof(void *) - 1));
/* Avoid NULL dereference if callback is NULL. */
if (WARN_ON_ONCE(!func))
return;
if (debug_rcu_head_queue(head)) { if (debug_rcu_head_queue(head)) {
/* /*
* Probable double call_rcu(), so leak the callback. * Probable double call_rcu(), so leak the callback.