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 DDC9EFC08 for ; Mon, 15 May 2023 17:36:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4137DC4339C; Mon, 15 May 2023 17:36:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1684172191; bh=ovHfEM0fyjLv6XsaWbJU/Bs5Arfg6u26HFvANVF/FWM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=s7NTaVHsU6yqfFhVV82HDMSqPnRjhm34jNYrVphJLUKYyykrzbal3Q8Gt5rK7z1Lw MDk4+7wWN2Nk9ju0cnhpo3hJgk1RBV2ieeDCBaeutPubdSrhiL9KiBnMdZpWZjGOxN RHygD0oEjlUkFS2Dux+u0+zULvWY0Rbkwdh0HeJk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jakub Kicinski , "Joel Fernandes (Google)" , Alexander Lobakin , Kees Cook Subject: [PATCH 5.10 034/381] kheaders: Use array declaration instead of char Date: Mon, 15 May 2023 18:24:45 +0200 Message-Id: <20230515161738.346763618@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230515161736.775969473@linuxfoundation.org> References: <20230515161736.775969473@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Kees Cook commit b69edab47f1da8edd8e7bfdf8c70f51a2a5d89fb upstream. Under CONFIG_FORTIFY_SOURCE, memcpy() will check the size of destination and source buffers. Defining kernel_headers_data as "char" would trip this check. Since these addresses are treated as byte arrays, define them as arrays (as done everywhere else). This was seen with: $ cat /sys/kernel/kheaders.tar.xz >> /dev/null detected buffer overflow in memcpy kernel BUG at lib/string_helpers.c:1027! ... RIP: 0010:fortify_panic+0xf/0x20 [...] Call Trace: ikheaders_read+0x45/0x50 [kheaders] kernfs_fop_read_iter+0x1a4/0x2f0 ... Reported-by: Jakub Kicinski Link: https://lore.kernel.org/bpf/20230302112130.6e402a98@kernel.org/ Acked-by: Joel Fernandes (Google) Reviewed-by: Alexander Lobakin Tested-by: Jakub Kicinski Fixes: 43d8ce9d65a5 ("Provide in-kernel headers to make extending kernel easier") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20230302224946.never.243-kees@kernel.org Signed-off-by: Greg Kroah-Hartman --- kernel/kheaders.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) --- a/kernel/kheaders.c +++ b/kernel/kheaders.c @@ -26,15 +26,15 @@ asm ( " .popsection \n" ); -extern char kernel_headers_data; -extern char kernel_headers_data_end; +extern char kernel_headers_data[]; +extern char kernel_headers_data_end[]; static ssize_t ikheaders_read(struct file *file, struct kobject *kobj, struct bin_attribute *bin_attr, char *buf, loff_t off, size_t len) { - memcpy(buf, &kernel_headers_data + off, len); + memcpy(buf, &kernel_headers_data[off], len); return len; } @@ -48,8 +48,8 @@ static struct bin_attribute kheaders_att static int __init ikheaders_init(void) { - kheaders_attr.size = (&kernel_headers_data_end - - &kernel_headers_data); + kheaders_attr.size = (kernel_headers_data_end - + kernel_headers_data); return sysfs_create_bin_file(kernel_kobj, &kheaders_attr); }