From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7AA7E42F707; Thu, 30 Jul 2026 15:05:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785423914; cv=none; b=AgxPlI3X8kzq2dhHhlmbC3UJb5eYIJ+/kwwlI3YvF4wzYDEx7K4dk9yvBTt+ttyWvUFZ3q4ZHiq6z41CKXcPQrE/2r+mNJq9l/Gs9OD+UM4CbwdEyRwk6eRRZ9HoPO9c8S6XgMRXfxS6ah7F44azhXgQ953bidcvg8gpy59P9Z4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785423914; c=relaxed/simple; bh=atimfeOvcUMUdjJqaE6ZdQaoS1XowooAprCsPz+NJ/Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bRYA7FgtrcxC2NX4VVE7uX0ZlsA7kFOP3qZNvqwyLNLW5dRlHigFxOfCPTllPs8YE+0HZ05jZaIxkQcggARkfGSNfA/G5yb8S+qQbnGmPTfHv/3kV2UzkSAO5DkCdRWEBmWdSEhhJ6Mn7fT5sB9mThUj57YOe5VtAzFO/HbQB0w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=OCov9ON2; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="OCov9ON2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6A251F000E9; Thu, 30 Jul 2026 15:05:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785423913; bh=bTbBEqTS0yu3OP75LxdzF993DMgJENFtACK/2HaJr4s=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=OCov9ON2xd0kk6t/C9KinQHCvzXOugAK6PLmRJZU/27BFBnqtgKjeChlLD/q6lMC7 oM/Bjr7bTwT6fE0ClRd4vgIuhUBGaRrMme4XlNplKBiPPbTXRcRQtwhT1YLuPWh5Iq 9nX7EyXoLaEh2SKHjYxP4LkXxt5MJP4Wc7zF49Yw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Tzung-Bi Shih , Guenter Roeck , Sasha Levin Subject: [PATCH 6.18 173/675] watchdog: pretimeout: Fix UAF in watchdog_unregister_governor() Date: Thu, 30 Jul 2026 16:08:23 +0200 Message-ID: <20260730141448.815112742@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141445.110192266@linuxfoundation.org> References: <20260730141445.110192266@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tzung-Bi Shih [ Upstream commit 7362ba0f9c96ac3ad6a2ca3995bd9fc9a28a8661 ] When a watchdog governor is unregistered, it updates existing watchdog devices that were using this governor by falling back to `default_gov`. If the governor being unregistered is currently set as `default_gov`, the `default_gov` is never cleared. This leads to 2 use-after-free issues: 1. New watchdog devices registered after this point will inherit the dangling `default_gov`. 2. Existing watchdog devices using the unregistered governor will have their `wdd->gov` reassigned to the dangling `default_gov`. Fix the UAF by clearing `default_gov` if it matches the governor being unregistered. Fixes: da0d12ff2b82 ("watchdog: pretimeout: add panic pretimeout governor") Signed-off-by: Tzung-Bi Shih Link: https://lore.kernel.org/r/20260707101803.3598173-1-tzungbi@kernel.org Signed-off-by: Guenter Roeck Signed-off-by: Sasha Levin --- drivers/watchdog/watchdog_pretimeout.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/watchdog/watchdog_pretimeout.c b/drivers/watchdog/watchdog_pretimeout.c index 2526436dc74dd8..ea05f84f07e184 100644 --- a/drivers/watchdog/watchdog_pretimeout.c +++ b/drivers/watchdog/watchdog_pretimeout.c @@ -167,6 +167,8 @@ void watchdog_unregister_governor(struct watchdog_governor *gov) } spin_lock_irq(&pretimeout_lock); + if (default_gov == gov) + default_gov = NULL; list_for_each_entry(p, &pretimeout_list, entry) if (p->wdd->gov == gov) p->wdd->gov = default_gov; -- 2.53.0