linux-kernel - [PATCH] rtc: check if __rtc_read_time was successful in rtc_timer_do

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <20241011043153.3788112-1-leonylgao@gmail.com>
Date: Fri, 11 Oct 2024 12:31:53 +0800
From: Yongliang Gao <leonylgao@...il.com>
To: alexandre.belloni@...tlin.com,
	john.stultz@...aro.org
Cc: linux-rtc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Yongliang Gao <leonylgao@...cent.com>,
	Jingqun Li <jingqunli@...cent.com>
Subject: [PATCH] rtc: check if __rtc_read_time was successful in rtc_timer_do_work()

From: Yongliang Gao <leonylgao@...cent.com>

If the __rtc_read_time call fails,, the struct rtc_time tm; may contain
uninitialized data, or an illegal date/time read from the RTC hardware.

When calling rtc_tm_to_ktime later, the result may be a very large value
(possibly KTIME_MAX). If there are periodic timers in rtc->timerqueue,
they will continually expire, may causing kernel softlockup.

Fixes: 6610e0893b8b ("RTC: Rework RTC code to use timerqueue for events")
Signed-off-by: Yongliang Gao <leonylgao@...cent.com>
Acked-by: Jingqun Li <jingqunli@...cent.com>
---
 drivers/rtc/interface.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
index cca650b2e0b9..aaf76406cd7d 100644
--- a/drivers/rtc/interface.c
+++ b/drivers/rtc/interface.c
@@ -904,13 +904,18 @@ void rtc_timer_do_work(struct work_struct *work)
 	struct timerqueue_node *next;
 	ktime_t now;
 	struct rtc_time tm;
+	int err;
 
 	struct rtc_device *rtc =
 		container_of(work, struct rtc_device, irqwork);
 
 	mutex_lock(&rtc->ops_lock);
 again:
-	__rtc_read_time(rtc, &tm);
+	err = __rtc_read_time(rtc, &tm);
+	if (err) {
+		mutex_unlock(&rtc->ops_lock);
+		return;
+	}
 	now = rtc_tm_to_ktime(tm);
 	while ((next = timerqueue_getnext(&rtc->timerqueue))) {
 		if (next->expires > now)
-- 
2.39.3