From: Zhan Xusheng Date: Tue, 7 Apr 2026 14:36:27 +0000 (+0800) Subject: alarmtimer: Access timerqueue node under lock in suspend X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=09c04714cb455debc1dcc3535b6becb52c5b01e0;p=thirdparty%2Fkernel%2Flinux.git alarmtimer: Access timerqueue node under lock in suspend In alarmtimer_suspend(), timerqueue_getnext() is called under base->lock, but next->expires is read after the lock is released. This is safe because suspend freezes all relevant task contexts, but reading the node while holding the lock makes the code easier to reason about and not worry about a theoretical UAF. Signed-off-by: Zhan Xusheng Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260407143627.19405-1-zhanxusheng@xiaomi.com --- diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index 069d93bfb0c75..7c07737bb5fff 100644 --- a/kernel/time/alarmtimer.c +++ b/kernel/time/alarmtimer.c @@ -234,19 +234,23 @@ static int alarmtimer_suspend(struct device *dev) if (!rtc) return 0; - /* Find the soonest timer to expire*/ + /* Find the soonest timer to expire */ for (i = 0; i < ALARM_NUMTYPE; i++) { struct alarm_base *base = &alarm_bases[i]; struct timerqueue_node *next; + ktime_t next_expires; ktime_t delta; - scoped_guard(spinlock_irqsave, &base->lock) + scoped_guard(spinlock_irqsave, &base->lock) { next = timerqueue_getnext(&base->timerqueue); + if (next) + next_expires = next->expires; + } if (!next) continue; - delta = ktime_sub(next->expires, base->get_ktime()); + delta = ktime_sub(next_expires, base->get_ktime()); if (!min || (delta < min)) { - expires = next->expires; + expires = next_expires; min = delta; type = i; }