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 9EB431F91F9; Sun, 26 Jan 2025 14:55:24 +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=1737903324; cv=none; b=r/gg7lBIaHbt/AXuSiyN9V3xQHSmAJoM3BJ0Wf7gUtr6aMQ9wWITkuVoBkkylIGHAzsywkntF2ecqBMh/GH+7WD22haAUBtSdwzD1ZYvQaQA6iBMWLunDbJal79BxJkHaaOzWGM4Xu4hM8HYwWmo59JU12vsE/jkbnX4g7nf0nM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737903324; c=relaxed/simple; bh=0aOUCKj0HZ3P1cz0RTZwl+fOFK1hYxwlHkUcJZoG6zQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=K9fu/qy5QeXQuw1kh7Vl/vnx1sfXZyCRykP6RixHBVZYmg8xk8Rg/xo2UbM807cekDzGoBg4H3yq8XK39kjz7PEaJOcz+SI/KyQ6pZv+7VENKYaYUI0j1J99GNI+lIwfq8uzXK08fD0p2DI1SZwa9v0BIcJbv5fI5Uo0+CqM5go= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Cdjdxman; 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="Cdjdxman" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 765D1C4CEE3; Sun, 26 Jan 2025 14:55:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737903324; bh=0aOUCKj0HZ3P1cz0RTZwl+fOFK1hYxwlHkUcJZoG6zQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Cdjdxman0heG/UvTde2Kxm2q71oa+WqjKek2Iuk345kL2d+DmF9tFEAwAKJFIqX0K kAeeyueRbEnNjcr7/QfwAaxQf9bYlfiz7YCtejoKt43j3ZWoOMFgrta3iaH3PfIm3e VM9YMy241iF0Y2ud4DFLLoMupMUIuc8eCXIv6BIcEiEQAcIhwldTM2JffrW2hU0uRa v8uvupMIz4nAyMDEowbCuQYnJMaUjDnbk15XkX6DyyyOpc3MlmJhCBLBTje2Ud3TvZ 8ZEEFM/z7T+Ae7VFvdgRFRI1vgnAft0sYnIBOjQa6e0DkVyOI6m4foUKL8FRqVJvNi 2mYGhu73Xbv8Q== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Kuan-Wei Chiu , Petr Mladek , Sasha Levin Subject: [PATCH AUTOSEL 6.12 11/31] printk: Fix signed integer overflow when defining LOG_BUF_LEN_MAX Date: Sun, 26 Jan 2025 09:54:27 -0500 Message-Id: <20250126145448.930220-11-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250126145448.930220-1-sashal@kernel.org> References: <20250126145448.930220-1-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 6.12.11 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 beb808f4c367b..ea0b2290e2d12 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