rseq: Protect event mask against membarrier IPI

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commit 6eb350a223 upstream.

rseq_need_restart() reads and clears task::rseq_event_mask with preemption
disabled to guard against the scheduler.

But membarrier() uses an IPI and sets the PREEMPT bit in the event mask
from the IPI, which leaves that RMW operation unprotected.

Use guard(irq) if CONFIG_MEMBARRIER is enabled to fix that.

Fixes: 2a36ab717e ("rseq/membarrier: Add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Thomas Gleixner 2025-08-13 17:02:30 +02:00 • committed by Greg Kroah-Hartman

parent 88025faf2a

commit 159e2db6cb

2 changed files with 13 additions and 8 deletions

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11

include/linux/rseq.h

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10

kernel/rseq.c

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