Commit 1e106aa3 authored Nov 06, 2020 by Dan Carpenter Committed by Thomas Gleixner Nov 09, 2020

futex: Don't enable IRQs unconditionally in put_pi_state()



The exit_pi_state_list() function calls put_pi_state() with IRQs disabled
and is not expecting that IRQs will be enabled inside the function.

Use the _irqsave() variant so that IRQs are restored to the original state
instead of being enabled unconditionally.

Fixes: 153fbd12 ("futex: Fix more put_pi_state() vs. exit_pi_state_list() races")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201106085205.GA1159983@mwanda

parent f8394f23

kernel/futex.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -788,8 +788,9 @@ static void put_pi_state(struct futex_pi_state *pi_state)
		*/
		if (pi_state->owner) {
		struct task_struct *owner;
		unsigned long flags;

		raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
		raw_spin_lock_irqsave(&pi_state->pi_mutex.wait_lock, flags);
		owner = pi_state->owner;
		if (owner) {
		raw_spin_lock(&owner->pi_lock);
		@@ -797,7 +798,7 @@ static void put_pi_state(struct futex_pi_state *pi_state)
		raw_spin_unlock(&owner->pi_lock);
		}
		rt_mutex_proxy_unlock(&pi_state->pi_mutex, owner);
		raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
		raw_spin_unlock_irqrestore(&pi_state->pi_mutex.wait_lock, flags);
		}

		if (current->pi_state_cache) {

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