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