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 5DEB23E0C5F; Mon, 17 Aug 2026 14:05:47 +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=1786975548; cv=none; b=hWrtnMD3u9AV0IlFn+I68VFL2ZJh6WJ4Pw1fPCK8/yhOvDSRGUgFFRtROYJ0TbPQhIcrHvq4JNHjHkj5ZxnqfErk0ov7T0rgDwyyO5yjSYGIvHLLaWSyFnJZEClitDcuqY/7p7xRLBK9n3NK+VUWlLoFb6api58VntARGcBUpng= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786975548; c=relaxed/simple; bh=oQGrC4J7TLRLU8QcnM49OFSasfHhGqlDX8O1JHUMv68=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NfREEu/ImUZbmvNJcq2klZFQCac+2b/f9vxbqj6x9bOSs4/4FMz3eFf4YTmI0BBFj1YbiUJDHY9i6ZDFen9KuXkth7jdl8v2aWc9uk+pTGMZZm0NYgHuJQF9j34U9juvoF3eCW9s4OBXVeTXSnAfK1NMAtoieUvYu/fK3aHf0aw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=YCytDXjA; 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="YCytDXjA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4E271F000E9; Mon, 17 Aug 2026 14:05:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786975547; bh=RuHqAWG5UkO3VCnTCV+WoyhKjLTJgTRLfWdRWR89tyw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=YCytDXjAHFeijgG4rXOxjdPCz0l12S8rEeDHDeI+IjEaMXLsFrfCHGIT+hhicrMKH Ab8s2caiIS4Eti12T0pcZ3FVycq9jop4zIs3I6S3PPHOcKVN+lUBoBrje1y65fe0kc SXTuGNKwOZlZIJ+/JsLPXBOElV2lvT26ognhyEDs= 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 5.10 063/389] watchdog: pretimeout: Fix UAF in watchdog_unregister_governor() Date: Mon, 17 Aug 2026 15:28:22 +0200 Message-ID: <20260817132541.552005425@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132538.796021292@linuxfoundation.org> References: <20260817132538.796021292@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 5.10-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 01ca84be240f6c..fe4c8ace9a4276 100644 --- a/drivers/watchdog/watchdog_pretimeout.c +++ b/drivers/watchdog/watchdog_pretimeout.c @@ -164,6 +164,8 @@ 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