From nobody Thu Apr 2 10:57:42 2026 Received: from mail-pf1-f174.google.com (mail-pf1-f174.google.com [209.85.210.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 44A5218EFD1 for ; Mon, 30 Mar 2026 06:16:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.174 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774851367; cv=none; b=b7PfUw7loyko1bMi7+iRYKONgvUWeQoiV00OsHdVhtT6K0Tbq02ZIJsfZui1eT8Mf+6GGFQXaxE12voTVSxbPiNE0hVeMTw7Tyged0pMz/V9yBgSTx/bDBHIcGQQEtstGq38E7MmMMgmTgYnkt9AWDm8dIlN6CyiYKSgYeS9/sY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774851367; c=relaxed/simple; bh=87mJjMAYNC63yx7FyzA6mAkxX4fnYMfYZcBQsKMZUWw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=kgD3u6kHDxWEgTjMvaxs2z37jW0jKo22QVtew+WQTB0K+A71E/i0YThX+agYEQ1ek5obUuhP24+fBqaKIm9YlfNEFkn06rtijdh3ce3gtYzndVBR4ruY/qf0g+E4Ta6t3JLiqi+VgyMTVe7E1aZePEwUltfDwkVFjnrqZSOQxjw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=gvjZUs3X; arc=none smtp.client-ip=209.85.210.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="gvjZUs3X" Received: by mail-pf1-f174.google.com with SMTP id d2e1a72fcca58-82a646c96bdso3360586b3a.2 for ; Sun, 29 Mar 2026 23:16:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1774851365; x=1775456165; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=osyRntjbr1QTJLtVYqnOdBR4kNK4obn4/JyjETDdtbE=; b=gvjZUs3XA/7vpXu5+vHP3N/IzN3sSJcnmIZmzCrR+jb/v4xZRWVwx9WVrQWvWEKkwr 9usIaZNPAEyE78CCsXv8gYdf5XjvLoPgE0+0EYeAo8qtKEtkDu6m9WYyPK8dlyZDnvHM rPcNSIZuq1aSOIyAYLerDtXNRvRtbi+JmQsGto/bTTK8QmCbKfYIuiu/57gMRBb8kDH4 fBwsCtOgiCwsBrnP4kmFckLanaxvz/xAGAFs6fXqx8oguy9ucHqwLBQxALUlz3NrPMFC x1hDl/b7SPcWYWj1p7ywl1xEiZWvfVhXwUQ262/5z66LnN+3eKOwfdlqbBrHAqJz74dx y7Ig== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774851365; x=1775456165; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=osyRntjbr1QTJLtVYqnOdBR4kNK4obn4/JyjETDdtbE=; b=jnbuz2DBW20pL3Ha/q+v3npKcSPqQGCt2R/mszM+7pzK/LLvSWRXG063BjyhLpRUsK vNg31SnV7DmG5nNpQZhJxd/u2veXl7/Dkwia831H7ySRoajOUJtOoYc9hoibnyEh22N7 mzPgWgxFD66pOf2IMhDXwiyu4OIj/GSjwz8jIs4cG6nIr6SXUwWNFlosoQeqjZcyQRo2 4jFl6b8gMVYuHD3Q8dpyHxagA/XneyZLgZX4fGjq+8llvM59EuXUU9WB3CN+7dIGng/Z ntB8ObuuFBdScSaUhSq8eaUYHcDlGWd2LS8nbdPo9RCpZQMWx1CGn6XH1sMin7MZpN2t fJmQ== X-Gm-Message-State: AOJu0YwlP2Rw7wQFtqbud8nui2DrMKrKxa4DrcM/5ywBC60ayeljb8lW f1Md1mXji6EMBXysz9nqAXitbnwB+sFsLqtq3xXSg28bJUkMJiSWP4fg X-Gm-Gg: ATEYQzzpOnf6lTolmpiitTpQZ9z8mTerD6K6vb5ywbdhxY1nihHtgZ7+NXkcjRVR7tc 9zzM2vjRdd0KqxKhyJXHTFFPum7r45SciI6NsF/PtBGV1UOdQd7JoU/5TzW8tcNJ+MMx1odqo13 2JmYh88vLj3lj54W5rXGtmViGU2iKla3FJDqHtBD3gj41tlQLNwDnDz3M1Dfz59+wmx1JjzbR8J Ec++RFjOy6EJvt9bOhBlVO9QJobg46zg7TNaPz2tDDy0/dRCdHHlZaDn4tDeU0G9l4n63qBjy+H JGxPkVRXCGUZthtY8QK8iR41dWdTvZc2JY/Cq6OzYo9gE/byMk8SYLl4ReD4WW4WZU+ZzQX5cOR lKxTbu9RM/rsT3c/66Izr/U6Q+mPsBUCluQQeayDZIa801tmpUzZNccQQfcfN0YtT10WWXhIWQR 1PZITLsRIkYQjwAGRVzQa8jUpB116IMrAeSaXwRbzt6f3UOO8= X-Received: by 2002:a05:6a00:4396:b0:824:93e4:2ddf with SMTP id d2e1a72fcca58-82c95aef81fmr11326550b3a.13.1774851365546; Sun, 29 Mar 2026 23:16:05 -0700 (PDT) Received: from DESKTOP-MOQC9AF.mioffice.cn ([43.224.245.237]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-82ca8464576sm6370610b3a.14.2026.03.29.23.16.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 29 Mar 2026 23:16:05 -0700 (PDT) From: Zhan Xusheng X-Google-Original-From: Zhan Xusheng To: Thomas Gleixner Cc: linux-kernel@vger.kernel.org, Zhan Xusheng Subject: [PATCH] alarmtimer: Fix use-after-free of timerqueue node in alarmtimer_suspend() Date: Mon, 30 Mar 2026 14:15:59 +0800 Message-ID: <20260330061559.8997-1-zhanxusheng@xiaomi.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In alarmtimer_suspend(), the timerqueue_node pointer 'next' is obtained under base->lock via scoped_guard(), but its members (next->expires) are accessed after the lock has been released when the scoped_guard goes out of scope. Between the lock release and the dereference, a concurrent timer cancellation on another CPU could remove and free the timerqueue node, leading to a use-after-free. Fix this by copying next->expires into a local ktime_t variable while still holding the lock. Signed-off-by: Zhan Xusheng --- 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 b64db405ba5c..6e173d70d825 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; =20 - /* Find the soonest timer to expire*/ + /* Find the soonest timer to expire */ for (i =3D 0; i < ALARM_NUMTYPE; i++) { struct alarm_base *base =3D &alarm_bases[i]; struct timerqueue_node *next; + ktime_t next_expires; ktime_t delta; =20 - scoped_guard(spinlock_irqsave, &base->lock) + scoped_guard(spinlock_irqsave, &base->lock) { next =3D timerqueue_getnext(&base->timerqueue); + if (next) + next_expires =3D next->expires; + } if (!next) continue; - delta =3D ktime_sub(next->expires, base->get_ktime()); + delta =3D ktime_sub(next_expires, base->get_ktime()); if (!min || (delta < min)) { - expires =3D next->expires; + expires =3D next_expires; min =3D delta; type =3D i; } --=20 2.43.0