From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B2682201278; Sun, 26 Jan 2025 14:57:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737903439; cv=none; b=S+mwIyiM3cANjLeJn2DPcgSzPn0JMdQKZj5PX6AyidV1pDGGn07YnDUOSg+Lis2MrJtAa+A0lPnI+PVDk5TYMyGI1Vp31qQ6S0A0ytOTQQHSjYYNa4l+7CQxoZd27m0yZ7Qupyjpxl0KW7QU8+CO28OaWRCRLlm36D+DSGfbQL0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737903439; c=relaxed/simple; bh=FGImjdNF9yPRRRy/Rd4yxbFcRQc9iCbQk34Sn9qvTdw=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=hMap7AP8I3DBodSfGaDo20l/bq4VLKFiL9mkuwLjZW/3sHnTOsooM4gZQ06yT5zuaPI3cRYQMXKFmS96X2uflg+IqxL+bqJOZEWxhgbfxCGUWCPpy8dAGBwPyZLxxFiIgw8NhPv1mgsKl0meDtV5rVnhtJnpBZHCWQGqhHnfhdY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gaEJF7L+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gaEJF7L+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EFAE0C4CEE5; Sun, 26 Jan 2025 14:57:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737903439; bh=FGImjdNF9yPRRRy/Rd4yxbFcRQc9iCbQk34Sn9qvTdw=; h=From:To:Cc:Subject:Date:From; b=gaEJF7L+rfNj6pTbWEMn0xRMnSVfPvf6yqLAKbUynA6wcKjF4CAtqndtp66e6WEsj TQoj0PWzsecU2rXSuH4zaVlEAwxZbJjuIT4qHegkpNK7exaZzAg9i7yM4kpej8gJoz xmiYD8Y+B41AUvS1hDZCdavw/85LjEEvEbknvLyNwu6FeU4orsWca9VD+BcxhSv4Uf fttCqsIXaAlaM7FlQLoU/2+p8fMkAZcvIYYKr/AlnZuCDgX32O/nEEoImSgAYIZHKk hdBvfq1vvNN6tib3zAZUIjNBx1SQyOJDFUY3JqSOuj/YgWF0FjbFofEYIlH2MUclFC SLHi58ZS3rMQg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Kuan-Wei Chiu , Petr Mladek , Sasha Levin Subject: [PATCH AUTOSEL 5.10 1/3] printk: Fix signed integer overflow when defining LOG_BUF_LEN_MAX Date: Sun, 26 Jan 2025 09:57:15 -0500 Message-Id: <20250126145717.946866-1-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.10.233 Content-Transfer-Encoding: 8bit From: Kuan-Wei Chiu [ Upstream commit 3d6f83df8ff2d5de84b50377e4f0d45e25311c7a ] Shifting 1 << 31 on a 32-bit int causes signed integer overflow, which leads to undefined behavior. To prevent this, cast 1 to u32 before performing the shift, ensuring well-defined behavior. This change explicitly avoids any potential overflow by ensuring that the shift occurs on an unsigned 32-bit integer. Signed-off-by: Kuan-Wei Chiu Acked-by: Petr Mladek Link: https://lore.kernel.org/r/20240928113608.1438087-1-visitorckw@gmail.com Signed-off-by: Petr Mladek Signed-off-by: Sasha Levin --- kernel/printk/printk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index a8af93cbc2936..3a7fd61c0e7be 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -420,7 +420,7 @@ static u64 clear_seq; /* record buffer */ #define LOG_ALIGN __alignof__(unsigned long) #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) -#define LOG_BUF_LEN_MAX (u32)(1 << 31) +#define LOG_BUF_LEN_MAX ((u32)1 << 31) static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); static char *log_buf = __log_buf; static u32 log_buf_len = __LOG_BUF_LEN; -- 2.39.5