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 4F1D417ADF8; Sun, 26 Jan 2025 14:53:53 +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=1737903235; cv=none; b=abaNPtXg1okNbkbipMDMmNoEwBLpA5oHfh8b6tAWw1qu+s/7wBmrlYGDvPEYocLK+6IG1OfoakWyAJb9BbPuj1MrBfcKXBlvvTlCrc5LR0loFtjUaws1/rKPGY1ZNRiyFoxLtwL7Tzc9OtjF7k21PWdOgnBACq2s/UNfgsWPwcs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737903235; c=relaxed/simple; bh=9n4p4UyWr0Xmb6GSq7HhDZHKtkqSg4PzLwwEamUTSBI=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=nHIy3zGLDiA+qyrojb1/jhrbx4E7W5RsJLAnYRixE7l8kkbt/Wu8b3rpt39dGLF5ZZ07jbdGG5MKirxWdOLa1Qo3EPwEJOswJyQ3WiB53xcC23/v8kxGwr9wgpK2XHFMR078iKs7NSY5NLTPy4SBx3x+nze+x3OTPoVZlJa/ASA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JFJwkI+3; 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="JFJwkI+3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 27C09C4CED3; Sun, 26 Jan 2025 14:53:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737903233; bh=9n4p4UyWr0Xmb6GSq7HhDZHKtkqSg4PzLwwEamUTSBI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JFJwkI+3ADpKNuFcJ6sjhee2r7MgnloY6C89eOmArw339OSJAJYrFFjK88fa2oXBq hLU0qNlLRSvQIJgLJWwcB1yC2wB9z3k6OpKll1c8hC6GPuRSoSpc+N7dbMgIOeam9o O2BLEV1xFlbHOjsT5iaUtb6tS5npsvryzbkzxPxZTvgEWn6GtZt5AE3YL641O8wp6P uf/cLf6RlublEm0TKywgzAz5o7f/rJfpIJhC0jsf0byq5y6Q9ONReYY+Vz6+Pp0YLM 3ldYK0ckOuV0XeHmcKcUW4y84oWL5JGvn0Htc1cyNbqFNRQOaK0PA62MwNCT38sWMd gjm0snDrY5Qfw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Kuan-Wei Chiu , Petr Mladek , Sasha Levin Subject: [PATCH AUTOSEL 6.13 12/34] printk: Fix signed integer overflow when defining LOG_BUF_LEN_MAX Date: Sun, 26 Jan 2025 09:52:48 -0500 Message-Id: <20250126145310.926311-12-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250126145310.926311-1-sashal@kernel.org> References: <20250126145310.926311-1-sashal@kernel.org> 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 6.13 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 80910bc3470c2..d8d82dd39dee8 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -523,7 +523,7 @@ static struct latched_seq 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