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 F37EA20101F; Sun, 26 Jan 2025 14:57:13 +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=1737903434; cv=none; b=eF2+11DtJsYahUElVEkigWhDw0BNeLJpuzAleSXprs5fyRIDWUg96bqkGqXdka4+kGsLlTBawAqO6sdbG0ZyLkgINi/33liVYw6jBejTBbZFF7ryha1h+W5hc7drPLrp7Nm9Ep6xEAmq1+QVb4kmxaLISO6kaNoZ1d4IRBEIMDw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737903434; c=relaxed/simple; bh=CwCieZey1HOpLg0h9YP4UHk5y5gLaSq8fmlaJ+qzid4=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=BC0zeHrkiWvcADfHLVC+Qz2tDNXdZh0/6/dQhgOp1ls1+iuSsEFEQIJspSk68dAvce9zYCVHbcTK+CtaXU3YrDHUSGzgabxZgvJkF2o8yAxkVxNJ4lBZQHCiXXAbM7S00aCh9o2WKMxPbB5NUUKiXNtQg+nxNyAz++oEQvW2fHM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=s66odchk; 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="s66odchk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3474BC4CEEA; Sun, 26 Jan 2025 14:57:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737903433; bh=CwCieZey1HOpLg0h9YP4UHk5y5gLaSq8fmlaJ+qzid4=; h=From:To:Cc:Subject:Date:From; b=s66odchk7OrcAnRi59vuqPNWvW6kJiGQB4N8+q1B0OAuvSa0jpcryKz4vfnDOhRzP SlQvgfIQRWesra9onshx4EjDNaTtnvJdWNNYZO2Ko/lCpgMCLxs8R0Cy9lTWBWH1nL IKPQ2lGOpYZX4C3bbT2mq15gB/TLEHOul4OTlPV+ly5/wQVwV4FzGi8V0O2oe1IbGR vdgS9LVYX9cTKSGzGNlsXBxxiXxiiwhPHH/T5hKreXJA70cLGhnJ8Jlqo6U/0lO1Jt kqsJU+Uf8adxT5TkBAvnTvOCdpntnxoM+xqMIUhijS6X446B8F2yR1XeGbL7LP1g3j wfsQ33DGnQwFQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Kuan-Wei Chiu , Petr Mladek , Sasha Levin Subject: [PATCH AUTOSEL 5.15 1/3] printk: Fix signed integer overflow when defining LOG_BUF_LEN_MAX Date: Sun, 26 Jan 2025 09:57:09 -0500 Message-Id: <20250126145711.946014-1-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 5.15.177 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 5e81d2a79d5cc..113990f38436e 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -403,7 +403,7 @@ 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