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 735C52036E2; Sun, 26 Jan 2025 14:57:25 +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=1737903445; cv=none; b=PqXyUFIWYou9YcXPK3Vtel7c+N9QMjknaFscYjYg+DfvD4JRyB2PsUN/Rf3SgXIH6WzFv7UsVfCwmezC1pEyz+yDh6jqj0WKsy6fCbrsGf5a5OXxTMKteaiIVsdA882YOHyxKngZhHf1RSr0bML/9MYng7LtZyfMU1VZlDkVems= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737903445; c=relaxed/simple; bh=ZYvqdzhrVmnNO+3ORASNZ7xcgMmpgeqgf3QL45CbMQo=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=rmA5BPwLQr6+F1UtIJEKuHgMPXehpnIFMFJNkfkaMIMFxCGs8NwFsr24g5knOk911EXsxmoSARKWrHrjQi2FetWW/5PbJMAObg3OshYwIZk+uB6WG+SkdvE/B8DcHz8x3Dhy2ggEMXhBIejeo61kGIk1rTdi0yzsjF4Bimlitm0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=PHUVnDfs; 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="PHUVnDfs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AAC0CC4CED3; Sun, 26 Jan 2025 14:57:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737903445; bh=ZYvqdzhrVmnNO+3ORASNZ7xcgMmpgeqgf3QL45CbMQo=; h=From:To:Cc:Subject:Date:From; b=PHUVnDfs5uYC1ALG+RwdzUgbYRkT2yePZ5idT+06SwcNYO+p2HIJezOeFLIEEYr71 bz1ebpkLU5JlOSdBTKiCv6aj7RsgvLvUIDe49f5MM95qFRGVkVgk6luWRCQZMyw372 Sm+9VgvoXJM/5BwcK7VTHD3iCYU4cGMpFM12q7B6YFG67MtqtoHOikuL7eCFHBtHKP 4iNrMgYya3AlflKVCHRp+9Z27gu/BswS/lr8rrvQZk3hSVxI4VbDqxuF+wX/KVQ9hf an6Ojis9VXXN64ImlaGxNMfq9Ia5k9EsAht8HVYKTKok42KUewOE7D35QMihyzzKSL hPwLU4FckJXwQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Kuan-Wei Chiu , Petr Mladek , Sasha Levin Subject: [PATCH AUTOSEL 5.4 1/2] printk: Fix signed integer overflow when defining LOG_BUF_LEN_MAX Date: Sun, 26 Jan 2025 09:57:22 -0500 Message-Id: <20250126145723.947855-1-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 5.4.289 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 ae1a97dd0c3cb..f6e1e154d9c18 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -457,7 +457,7 @@ static u32 clear_idx; /* record buffer */ #define LOG_ALIGN __alignof__(struct printk_log) #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