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 1ED4543C04B; Thu, 30 Jul 2026 16:01:37 +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=1785427299; cv=none; b=ob00l7dus/rNePV7Xmyjc5piSVmn8cesmubGlnooX7958/mfyGM1DXbxyHNbXYjH2AK+Vnt/nU8sw01YiD/maFNJmVzk660k94vmvAvVCsZnkjv+IrWpCGhbsnelsDuj7LLrqJGk3S/Q8vQn4HqEF+Th45/HEQC23P4r1RhECXo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785427299; c=relaxed/simple; bh=9seTzeZMZo3V/HUTwHNnRhcOFzAAS/ey6ZjeaD8rp40=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Juex+yb1FLzhSO2oj1+N4zzJrM9XaQX50y6j1jTudxQsg6fHPrfPjKWpcdS7XGQHYxdiyFS5gxt0T60ebRwcG5zen/9jK+rjPOb6VAClOAnPlZc5W7DI7iwD89MWxzVG6X4WP2lHwtyaZqhabLZ9BxNIYKPf5T07LCTUI12ktv4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rBP3omF3; 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="rBP3omF3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 566D31F000E9; Thu, 30 Jul 2026 16:01:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785427297; bh=gPNu/sUVUkfCL4homCbRguMRn8KGl5xOrWl7U64tTh4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=rBP3omF39aN6ILxqS9WKTNEbAIe1Eg9s5TY6aPKVAu1Xr/Af/Z4k9WoMSXWREvatX JytDy14xiz8ZR0r3Ltux4swmj7uoD0QD158W50wEeia8VqSRhYCMl+RsraxI0zkIA1 yxwLsPh45w3TCxYFEuW44rwkrNq/DyCKsJzSPVE0= 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 6.6 120/484] watchdog: pretimeout: Fix UAF in watchdog_unregister_governor() Date: Thu, 30 Jul 2026 16:10:17 +0200 Message-ID: <20260730141426.066582788@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141423.392222816@linuxfoundation.org> References: <20260730141423.392222816@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 6.6-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 e5295c990fa1b8..787b6227b8ccc3 100644 --- a/drivers/watchdog/watchdog_pretimeout.c +++ b/drivers/watchdog/watchdog_pretimeout.c @@ -165,6 +165,8 @@ 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