This is a note to let you know that I've just added the patch titled
futex: Don't enable IRQs unconditionally in put_pi_state()
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
futex-don-t-enable-irqs-unconditionally-in-put_pi_state.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Mar 4 02:09:29 PM CET 2021
From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Date: Mon, 1 Mar 2021 18:32:02 +0100
Subject: futex: Don't enable IRQs unconditionally in put_pi_state()
To: stable@xxxxxxxxxxxxxxx
Cc: Lee Jones <lee.jones@xxxxxxxxxx>, "Luis Claudio R. Goncalves" <lgoncalv@xxxxxxxxxx>
Message-ID: <YD0lErDoywqSJyM8@xxxxxxxxxxxxxxx>
Content-Disposition: inline
From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
commit 1e106aa3509b86738769775969822ffc1ec21bf4 upstream.
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: 153fbd1226fb ("futex: Fix more put_pi_state() vs. exit_pi_state_list() races")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20201106085205.GA1159983@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 4.9: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/futex.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -882,10 +882,12 @@ static void put_pi_state(struct futex_pi
* and has cleaned up the pi_state already
*/
if (pi_state->owner) {
- raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&pi_state->pi_mutex.wait_lock, flags);
pi_state_update_owner(pi_state, NULL);
rt_mutex_proxy_unlock(&pi_state->pi_mutex);
- 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) {
Patches currently in stable-queue which might be from ben@xxxxxxxxxxxxxxx are
queue-4.9/futex-cleanup-refcounting.patch
queue-4.9/futex-fix-more-put_pi_state-vs.-exit_pi_state_list-races.patch
queue-4.9/futex-futex_unlock_pi-determinism.patch
queue-4.9/futex-cleanup-variable-names-for-futex_top_waiter.patch
queue-4.9/futex-don-t-enable-irqs-unconditionally-in-put_pi_state.patch
queue-4.9/futex-fix-pi_state-owner-serialization.patch
queue-4.9/futex-pull-rt_mutex_futex_unlock-out-from-under-hb-lock.patch
