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 B24051CBA02; Sun, 26 Jan 2025 14:56:16 +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=1737903376; cv=none; b=WP8/fN6at/ro45OtBf/b2B5JDAh/bkIIpPIYsfwdHCHbNq90WOKi+d8kPHDcZsN32+0h/V8DwLes0Mtw6UtYemS9LJcPNZTMTbuq3stbT60erG+Gc5UeKY1xdyiNQUfxG4fYYSgrM2OIF/Nqush02ns5HovH36AVZQ7ZqbHc0h0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737903376; c=relaxed/simple; bh=Tdm/EnYLhmTz4f56Biulj5irNvRuRL3QnqC+X7PqT3I=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=qVqwuaWBoF01bfLxK6k+anAU/hl03t3B4UzlVeoD2PuEkdEDyWsjWg2nHF3vsVyVFIGr9/wozNQ96I1QBPrL/Lu/pshBlHQhfDs6BvxuW+L5SpBjkAInBauPrU2kHh8sJvEUlTIU/cUUlNGFzZQKwMbc6itMXFz+yQ2Vjg6W8kE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MRxvUDTc; 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="MRxvUDTc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E8843C4CEE3; Sun, 26 Jan 2025 14:56:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737903376; bh=Tdm/EnYLhmTz4f56Biulj5irNvRuRL3QnqC+X7PqT3I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MRxvUDTcQZMhK8hiy3JmE5150Fnt9jc4etFPGreEFvKJfuqkMm6Bbg1D/HakCfUHd ND7DUTRWFJwGhC+3SFVmHIXdSV8vSVWocgXNjZMRe+oLr0Nlm/sy57DPpNS3GLxIo3 B0n0lxttA3cqIAfOEZRF4WIi6vq7TvfO5Jg8tOpteixbWUB2+G/7yf6cMl/rgNV/yc aUjv4A3unnuyqG4GoLzRtf2W79ZS37NWrAD+oZR7CmavwfpzKau76iMb58J0G/2ZAJ 0DVxF20Pl828IG/tzeW6luEcpo8zc6BhEcRFk+3Ih1aoe3J6UnzxL6aQZgUx+EZEWe 8f/FOXRoO1Vpw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Kuan-Wei Chiu , Petr Mladek , Sasha Levin Subject: [PATCH AUTOSEL 6.6 02/17] printk: Fix signed integer overflow when defining LOG_BUF_LEN_MAX Date: Sun, 26 Jan 2025 09:55:57 -0500 Message-Id: <20250126145612.937679-2-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250126145612.937679-1-sashal@kernel.org> References: <20250126145612.937679-1-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 6.6.74 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 0fca282c0a254..dcdf449615bda 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -474,7 +474,7 @@ 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