fdc2316c60
Use AlmaLinux OS secure boot cert
Enable Btrfs support for all kernel variants
KVM: x86: check for invalid/obsolete root after making MMU pages available {CVE-2026-64561}
hpsa: bring back deprecated PCI ids #CFHack #CFHack2024
mptsas: bring back deprecated PCI ids #CFHack #CFHack2024
megaraid_sas: bring back deprecated PCI ids #CFHack #CFHack2024
qla2xxx: bring back deprecated PCI ids #CFHack #CFHack2024
qla4xxx: bring back deprecated PCI ids
be2iscsi: bring back deprecated PCI ids
kernel/rh_messages.h: enable all disabled pci devices by moving to unmaintained
gve: update QPL page registration logic to honor max_registered_pages (backport from upstream)
gve: enable reading max ring size from the device in DQO-QPL mode (backport from upstream)
95 lines
3.9 KiB
Diff
95 lines
3.9 KiB
Diff
From 449e173e733a3f8bb9186785fc48265fbcfd8956 Mon Sep 17 00:00:00 2001
|
|
From: Waiman Long <longman@redhat.com>
|
|
Date: Mon, 9 Mar 2026 23:09:28 -0400
|
|
Subject: [PATCH] timers: Fix NULL function pointer race in
|
|
timer_shutdown_sync()
|
|
|
|
JIRA: https://issues.redhat.com/browse/RHEL-152433
|
|
CVE: CVE-2025-68214
|
|
|
|
commit 20739af07383e6eb1ec59dcd70b72ebfa9ac362c
|
|
Author: Yipeng Zou <zouyipeng@huawei.com>
|
|
Date: Sat, 22 Nov 2025 09:39:42 +0000
|
|
|
|
timers: Fix NULL function pointer race in timer_shutdown_sync()
|
|
|
|
There is a race condition between timer_shutdown_sync() and timer
|
|
expiration that can lead to hitting a WARN_ON in expire_timers().
|
|
|
|
The issue occurs when timer_shutdown_sync() clears the timer function
|
|
to NULL while the timer is still running on another CPU. The race
|
|
scenario looks like this:
|
|
|
|
CPU0 CPU1
|
|
<SOFTIRQ>
|
|
lock_timer_base()
|
|
expire_timers()
|
|
base->running_timer = timer;
|
|
unlock_timer_base()
|
|
[call_timer_fn enter]
|
|
mod_timer()
|
|
...
|
|
timer_shutdown_sync()
|
|
lock_timer_base()
|
|
// For now, will not detach the timer but only clear its function to NULL
|
|
if (base->running_timer != timer)
|
|
ret = detach_if_pending(timer, base, true);
|
|
if (shutdown)
|
|
timer->function = NULL;
|
|
unlock_timer_base()
|
|
[call_timer_fn exit]
|
|
lock_timer_base()
|
|
base->running_timer = NULL;
|
|
unlock_timer_base()
|
|
...
|
|
// Now timer is pending while its function set to NULL.
|
|
// next timer trigger
|
|
<SOFTIRQ>
|
|
expire_timers()
|
|
WARN_ON_ONCE(!fn) // hit
|
|
...
|
|
lock_timer_base()
|
|
// Now timer will detach
|
|
if (base->running_timer != timer)
|
|
ret = detach_if_pending(timer, base, true);
|
|
if (shutdown)
|
|
timer->function = NULL;
|
|
unlock_timer_base()
|
|
|
|
The problem is that timer_shutdown_sync() clears the timer function
|
|
regardless of whether the timer is currently running. This can leave a
|
|
pending timer with a NULL function pointer, which triggers the
|
|
WARN_ON_ONCE(!fn) check in expire_timers().
|
|
|
|
Fix this by only clearing the timer function when actually detaching the
|
|
timer. If the timer is running, leave the function pointer intact, which is
|
|
safe because the timer will be properly detached when it finishes running.
|
|
|
|
Fixes: 0cc04e80458a ("timers: Add shutdown mechanism to the internal functions")
|
|
Signed-off-by: Yipeng Zou <zouyipeng@huawei.com>
|
|
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
|
|
Cc: stable@vger.kernel.org
|
|
Link: https://patch.msgid.link/20251122093942.301559-1-zouyipeng@huawei.com
|
|
|
|
Signed-off-by: Waiman Long <longman@redhat.com>
|
|
|
|
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
|
|
index 1391ea8..9b61f99 100644
|
|
--- a/kernel/time/timer.c
|
|
+++ b/kernel/time/timer.c
|
|
@@ -1458,10 +1458,11 @@ static int __try_to_del_timer_sync(struct timer_list *timer, bool shutdown)
|
|
|
|
base = lock_timer_base(timer, &flags);
|
|
|
|
- if (base->running_timer != timer)
|
|
+ if (base->running_timer != timer) {
|
|
ret = detach_if_pending(timer, base, true);
|
|
- if (shutdown)
|
|
- timer->function = NULL;
|
|
+ if (shutdown)
|
|
+ timer->function = NULL;
|
|
+ }
|
|
|
|
raw_spin_unlock_irqrestore(&base->lock, flags);
|
|
|