From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from devianza.investici.org (devianza.investici.org [198.167.222.108]) (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 E4DC447AF69; Tue, 18 Aug 2026 16:38:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.167.222.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787071096; cv=none; b=OitNClmMxKGq+Nf3bbf2Q79cPXq9nridJCg1Z5pz1qGHdyk5yTUP73atdVZY5qIsH++nuIus0yN1Bsri3OeXNo2QMFVKWyB8e5tk2cRFp1lpb1BXNLEv7dSMEhbiTcuTCoxeKIksU/smFsrNdep/Mwu5uWhOc3Jytp56Ex5dSCg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787071096; c=relaxed/simple; bh=NiGA6AXye8cZ/IcxBjpZ+kHZGi8lvXQ6kFgbZD0Lok8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=B8A0dwn9rgF17xTOfWDdjOf2f4AK3fKauN2b/+40xzbvPVA5F9AIOuj+ddHGITDwpXlZPXMAukR70pfToAgtV/2htiGnxhxSok8X1PvNMvgeb1xn9LkGnuNIpmjTGbYdhlUnTDoNdbkG+MaOlpAhRYPM4relYrfZ5Vu1plOo7N8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=grrlz.net; spf=pass smtp.mailfrom=grrlz.net; dkim=pass (1024-bit key) header.d=grrlz.net header.i=@grrlz.net header.b=Umr8blve; arc=none smtp.client-ip=198.167.222.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=grrlz.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=grrlz.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=grrlz.net header.i=@grrlz.net header.b="Umr8blve" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=grrlz.net; s=stigmate; t=1787071090; bh=zk9npSmxa7h2iYAfiMla7unhtV1PsNEB/GA3nn0UEss=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Umr8blveLBUGt/5l1/+WgNuWo7DMBmgBGQ7ShSbpiO33Qa3UNSme3YDCqN0jRPoRl 0wxVyVPt5w7ldM89/Znf470VZFXC2kp5fYyGV2tqyl6cJTDa8E5zNVjrre0tDGhELI hh33m/gP/f/UQD6bfwxpF8WuoLtEyMOgMwGUSdWs= Received: from mx2.investici.org (unknown [127.0.0.1]) by devianza.investici.org (Postfix) with UTF8SMTP id 4hPb3k5wW9z6vLM; Tue, 18 Aug 2026 16:38:10 +0000 (UTC) Received: by mx2.investici.org (Postfix) id 4hPb3k3bHqz4y6W; Tue, 18 Aug 2026 16:38:10 +0000 (UTC) From: Bradley Morgan To: Andrew Morton Cc: Petr Mladek , Jinchao Wang , Feng Tang , Rio , Pnina Feder , Petr Pavlu , Sergey Senozhatsky , linux-kernel@vger.kernel.org, Bradley Morgan , Sashiko , stable@vger.kernel.org Subject: [PATCH v6 3/6] panic: fix va_list reuse in panic_try_force_cpu() Date: Tue, 18 Aug 2026 16:38:03 +0000 Message-ID: <20260818163806.17460-4-include@grrlz.net> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260818163806.17460-1-include@grrlz.net> References: <20260818163806.17460-1-include@grrlz.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit vsnprintf() consumes the caller's va_list. When the redirect fails, vpanic() reuses it for the panic message, which is undefined behavior. Use va_copy(). Fixes: 2e171ab29f91 ("panic: add panic_force_cpu= parameter to redirect panic to a specific CPU") Cc: stable@vger.kernel.org Reviewed-by: Petr Mladek Signed-off-by: Bradley Morgan --- kernel/panic.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/panic.c b/kernel/panic.c index e1b443150ba0..6b5728c3c9ce 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -417,7 +417,12 @@ static bool panic_try_force_cpu(const char *fmt, va_list args) * fall back to static message for early boot panics or allocation failure. */ if (panic_force_buf) { - vsnprintf(panic_force_buf, PANIC_MSG_BUFSZ, fmt, args); + va_list ap; + + /* Do not consume args, the caller reuses it if we fail */ + va_copy(ap, args); + vsnprintf(panic_force_buf, PANIC_MSG_BUFSZ, fmt, ap); + va_end(ap); msg = panic_force_buf; } else { msg = "Redirected panic (buffer unavailable)"; -- 2.47.3