diff options
| author | Frederic Weisbecker <frederic@kernel.org> | 2024-06-21 12:16:01 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-08-03 09:54:27 +0300 |
| commit | 104e258a004037bc7dba9f6085c71dad6af57ad4 (patch) | |
| tree | 38c16bdd75a3bf0eed500a651586af336351cab4 /include/linux | |
| parent | 05d3fd599594abf79aad4484bccb2b26e1cb0b51 (diff) | |
| download | linux-104e258a004037bc7dba9f6085c71dad6af57ad4.tar.xz | |
perf: Fix event leak upon exec and file release
commit 3a5465418f5fd970e86a86c7f4075be262682840 upstream.
The perf pending task work is never waited upon the matching event
release. In the case of a child event, released via free_event()
directly, this can potentially result in a leaked event, such as in the
following scenario that doesn't even require a weak IRQ work
implementation to trigger:
schedule()
prepare_task_switch()
=======> <NMI>
perf_event_overflow()
event->pending_sigtrap = ...
irq_work_queue(&event->pending_irq)
<======= </NMI>
perf_event_task_sched_out()
event_sched_out()
event->pending_sigtrap = 0;
atomic_long_inc_not_zero(&event->refcount)
task_work_add(&event->pending_task)
finish_lock_switch()
=======> <IRQ>
perf_pending_irq()
//do nothing, rely on pending task work
<======= </IRQ>
begin_new_exec()
perf_event_exit_task()
perf_event_exit_event()
// If is child event
free_event()
WARN(atomic_long_cmpxchg(&event->refcount, 1, 0) != 1)
// event is leaked
Similar scenarios can also happen with perf_event_remove_on_exec() or
simply against concurrent perf_event_release().
Fix this with synchonizing against the possibly remaining pending task
work while freeing the event, just like is done with remaining pending
IRQ work. This means that the pending task callback neither need nor
should hold a reference to the event, preventing it from ever beeing
freed.
Fixes: 517e6a301f34 ("perf: Fix perf_pending_task() UaF")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240621091601.18227-5-frederic@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/perf_event.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index e846f87e2d09..95d4118ee4a9 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -786,6 +786,7 @@ struct perf_event { struct irq_work pending_irq; struct callback_head pending_task; unsigned int pending_work; + struct rcuwait pending_work_wait; atomic_t event_limit; |