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 80300435AB0; Thu, 30 Jul 2026 14:29:23 +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=1785421764; cv=none; b=b1R3r+0/q1n1SrKFcssJIX3hkJEC7RfmTzjQx5UMpNghurLX2AUEU5ocEIAtGn/754Hxaouzo3RmwJg/UrEf+XN4hgKIXWTAOc/HUv+dOccTKJsgWAJVc3lqAhJurONlLeJKNT0AftLx10pSlQ9auxBIA7p5uwX0zFDQ3bRZYTs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785421764; c=relaxed/simple; bh=0JKF9PpR3k3oQW7/IE9vh4JOehb64u8f3j9OfwssKa8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TBifXdeQTBmYKD4sh1dnNfWBoBHbmV4zOr6uCiHm2fh44Q5HyPw/RHfQ4YMelN/gTbPkuSHHrHRInAAcmP+ZZ9u10/8+FTmEOquBohzVt6RWdNjxh9xBopgBJHNNXkJZz9o6nZvYd+tUiUcAmmbIq02A0DERODQw6ROsMmSgoV0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ajBESriP; 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="ajBESriP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DA0BC1F000E9; Thu, 30 Jul 2026 14:29:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785421763; bh=+hfogXW0rauS0pCr1gLrscOE6h4fnSSB/Nk6Yk0ocBM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ajBESriP/n/VK+W8m4GEWbfU+Sao5qOGVNgd+7JkLWuDcL2TcaIOyWRctBRPPpKG0 lqou8tlIOdwNwiuknUmyEZCm76lTgMiBIllF8J1SZS8oNJ1mJs8osLlkErpbSpaeCn CJdC0RcxaHdoViwOxcx8fCJF2G5/YdQioyZEc9lI= 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 7.1 176/744] watchdog: pretimeout: Fix UAF in watchdog_unregister_governor() Date: Thu, 30 Jul 2026 16:07:29 +0200 Message-ID: <20260730141448.028537028@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141444.267951807@linuxfoundation.org> References: <20260730141444.267951807@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 7.1-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 19eb2ed2c7cb0e..02e09b9e396dab 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