From 09c04714cb455debc1dcc3535b6becb52c5b01e0 Mon Sep 17 00:00:00 2001 From: Zhan Xusheng Date: Tue, 7 Apr 2026 22:36:27 +0800 Subject: 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 --- kernel/time/alarmtimer.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index 069d93bfb0c7..7c07737bb5ff 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; } -- cgit v1.2.3