From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 EF1F24AA572; Thu, 10 Sep 2026 15:15:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789053334; cv=none; b=ktcWM8F9715vGLVOP0+N5oCOkT1dOiRkZ2P11MvGpy9LXdBUYTTIs43vR6TtYiBvDp3wuolt6QlOjLMfrQ+X39NMa1BRmoLi8cXDfpQQjBe58o1qNZtPZHT+azsYxbNBLUR/eJdM28xEBs2XZlT/x2FUSpTpWtE1d5oNqFL5vGg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789053334; c=relaxed/simple; bh=JLOuAk5tl3QZRZux1cWV0A6sqt+w4ImTvKCs0+yKnK0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=fSSUN46ZIED6iANfcQ8l62KOolwOCXHuLUZDHRAMks+srCkUbrOhUH9IZ9Ph87hb4v0D+Ty7SngZwCb27M1x4DY1yREr28FxLbN/OV1+F5VfYGicrkrYO0RBtp+Doz2vXXHBAWB6+ywEzoTsxgZfy+LQww8olSfC7fwVUx03XKA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HXY3/T+Y; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HXY3/T+Y" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 732FA1F00898; Thu, 10 Sep 2026 15:15:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789053329; bh=zdTTFikfWrYdC44mS2BXIE3fNsajuaVWVur6OX38iBA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=HXY3/T+Y6UX6bXebxHekTnO45aZV3GuIKKiVH8UkEVFvM1X+DvEuSZnm+7n3/dRtA D/4IxwgMhxwbC3jr3dux4gnQcQMj5vmHomMtETi4iQU6DowEwgXJ7iRb1yVUgM96sJ v/6dAestcxjTZTrzXxkBfY6B8DESPTlT56BnQu92MBDuw3NnIUslINpiFXxci7ecu4 isqM+4YW9TJLm3BWmhjuH71tYKPV7qOuxbGO/4bLyYYdXzx++XUrvcMcaC5Dx3mAPN 0QpLZ2fd86pm9vRpwfG1+5Ov9qOcsQbl0WZOkMUWw86cyfU5XqrUsi37thcxuMxYNn Gz4kGt9V2KfrA== From: "Masami Hiramatsu (Google)" To: Masami Hiramatsu , Andrew Morton , Breno Leitao , Christian Brauner , Thomas Gleixner , Ryan Roberts , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , Douglas Anderson , Huacai Chen Cc: Mark Rutland , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Sang-Heon Jeon Subject: [PATCH v4 1/2] tools/bootconfig: Fix integer overflow and truncation in size checks Date: Fri, 11 Sep 2026 00:15:24 +0900 Message-ID: <178905332413.213925.3179977110281463499.stgit@devnote2> X-Mailer: git-send-email 2.43.0 In-Reply-To: <178905331374.213925.295025394754459843.stgit@devnote2> References: <178905331374.213925.295025394754459843.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit From: Masami Hiramatsu (Google) Sashiko reported that on 32-bit systems, if an attacker crafts size in the bootconfig footer such that adding BOOTCONFIG_FOOTER_SIZE wraps around (for instance, if size is 0xFFFFFFFF), the size check in load_xbc_from_initrd() can be bypassed: if (stat.st_size < size + BOOTCONFIG_FOOTER_SIZE) { pr_err("bootconfig size is too big\n"); return -E2BIG; } Furthermore, on 64-bit systems with an initrd > 4.29 GB, comparing a corrupted 32-bit size (e.g. 0xFFFFFFFF) against stat.st_size - BOOTCONFIG_FOOTER_SIZE can also bypass the check if size is not bounded. Similarly, load_xbc_file() passes 64-bit stat.st_size directly into the 32-bit int size parameter of load_xbc_fd(), truncating large standalone files (>= 2GB). In both cases, passing 0xFFFFFFFF to load_xbc_fd() truncates to -1, resulting in malloc(0), an integer overflow in read(), and an out-of-bounds null-byte write. Fix this by: 1. Rejecting size > XBC_DATA_MAX or size > stat.st_size - BOOTCONFIG_FOOTER_SIZE in load_xbc_from_initrd(). 2. Rejecting stat.st_size > XBC_DATA_MAX in load_xbc_file() before passing it to load_xbc_fd(). 3. Checking size < 0 || size > XBC_DATA_MAX defensively in load_xbc_fd(). Fixes: 950313ebf79c ("tools: bootconfig: Add bootconfig command") Cc: stable@vger.kernel.org Reported-by: Sashiko Closes: https://lore.kernel.org/all/20260909161113.16C691F00A3A@smtp.kernel.org/ Closes: https://lore.kernel.org/all/20260910010137.EE0431F000FF@smtp.kernel.org/ Assisted-by: Antigravity:gemini-3.8-flash Signed-off-by: Masami Hiramatsu (Google) --- Changes in v3: - Reject size > XBC_DATA_MAX and size > stat.st_size - BOOTCONFIG_FOOTER_SIZE in load_xbc_from_initrd() to prevent bypass on initrd > 4.29 GB. - Check stat.st_size > XBC_DATA_MAX in load_xbc_file() to prevent truncation on large standalone files. - Check size < 0 || size > XBC_DATA_MAX defensively in load_xbc_fd(). Changes in v2: - Add Cc: stable. - Also reject if "size > XBC_DATA_MAX", that is obviously wrong. --- tools/bootconfig/main.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c index 7dc9fff9b637..17d971d47f87 100644 --- a/tools/bootconfig/main.c +++ b/tools/bootconfig/main.c @@ -140,6 +140,9 @@ static int load_xbc_fd(int fd, char **buf, int size) { int ret; + if (size < 0 || size > XBC_DATA_MAX) + return -EINVAL; + *buf = malloc(size + 1); if (!*buf) return -ENOMEM; @@ -168,6 +171,13 @@ static int load_xbc_file(const char *path, char **buf) return ret; } + if (stat.st_size > XBC_DATA_MAX) { + pr_err("%s size is too big\n", path); + ret = -E2BIG; + close(fd); + return ret; + } + ret = load_xbc_fd(fd, buf, stat.st_size); close(fd); @@ -218,7 +228,8 @@ static int load_xbc_from_initrd(int fd, char **buf) csum = le32toh(csum); /* Wrong size error */ - if (stat.st_size < size + BOOTCONFIG_FOOTER_SIZE) { + if (size > XBC_DATA_MAX || + size > stat.st_size - BOOTCONFIG_FOOTER_SIZE) { pr_err("bootconfig size is too big\n"); return -E2BIG; }