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 628A8457E72; Thu, 10 Sep 2026 21:27:45 +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=1789075666; cv=none; b=iNUNRK/Ga3gfhoW92N+CplMHY1clxn0hNvX9yLa80Yveqz3KlTtMJh6HgmwqHFqgqMY+/plWVNHK6gR045hPz8dXJ/QaKHpqgYRgFbt4CBJ3a+H8/90UTZWKbaNwjHCNPlYnFmJOWEwuZsm6x3TpyLKXUfhAGTbSnhHOjuso/PQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789075666; c=relaxed/simple; bh=7tAqaRehMHEU8uWxnjoXz+mryo06HhA4C4Db1j+UyOg=; h=Date:To:From:Subject:Message-Id; b=PEnPmRs21p7H879CcETkcvx+YIUfSqkdkZUy9m5mhuPTd6TTfuVElqdjPmZDqoUSSHlc2V1r+7+7+yXFoYrIW2e6OOvqEpI2D6f8D1xO4UJq2ZfH1PP18TvRtapfTxeHck3x+tznQUodf2Tzuhw+8WZSymKptkQocCkrmA7Fv0k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=a86RSJ7F; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="a86RSJ7F" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DA5981F000FF; Thu, 10 Sep 2026 21:27:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789075665; bh=LcbLrY4y6WN8w69xeReRON/wjrhqI2NlULJquItNuxE=; h=Date:To:From:Subject; b=a86RSJ7F5S+GRZI633oFTBHsCOy1/agRqYSYVz1YVk/2dB58MQU2jUXMtnAq6/bXd EKssgAFf83xXeSHlj6NRH4V8FiPg+e04H8zDd2apRyCYWe6Q1iuO76jMbwLuSKM8Tw s2jevRKcGOinW39JGz20CyqNMJFbO/sAoWrUovug= Date: Thu, 10 Sep 2026 14:27:44 -0700 To: mm-commits@vger.kernel.org,thomas.weissschuh@linutronix.de,stable@vger.kernel.org,sashiko-bot@kernel.org,ryan.roberts@arm.com,mark.rutland@arm.com,leitao@debian.org,ekffu200098@gmail.com,dianders@chromium.org,chenhuacai@kernel.org,brauner@kernel.org,mhiramat@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + bootconfig-fix-integer-overflow-in-initrd-size-check.patch added to mm-nonmm-unstable branch Message-Id: <20260910212744.DA5981F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: bootconfig: fix integer overflow in initrd size check has been added to the -mm mm-nonmm-unstable branch. Its filename is bootconfig-fix-integer-overflow-in-initrd-size-check.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/bootconfig-fix-integer-overflow-in-initrd-size-check.patch This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Masami Hiramatsu (Google) Subject: bootconfig: fix integer overflow in initrd size check Date: Fri, 11 Sep 2026 00:15:34 +0900 Sashiko reported that in get_boot_config_from_initrd(), a crafted initrd with a huge bootconfig size (such as 0xFFFFFFFF) can cause the pointer arithmetic: data = ((void *)hdr) - size; to wrap around on 32-bit systems (or when pointer subtraction overflows). Because data wraps around, the subsequent bounds check: if ((unsigned long)data < initrd_start) evaluates to false, bypassing the check. The kernel then calls xbc_calc_checksum(data, size), which attempts to read 4GB of memory, hitting unmapped pages and triggering a fatal kernel page fault during early boot. Furthermore, on 64-bit systems with an initrd > 4.29 GB, an unbounded 32-bit size can similarly bypass the initrd_start check. Fix this by: 1. Ensuring the initrd is at least large enough to contain the bootconfig footer and verifying hdr is within the initrd bounds. 2. Checking that size does not exceed XBC_DATA_MAX and does not exceed the available space between initrd_start and hdr before performing pointer subtraction. Link: https://lore.kernel.org/178905333479.213925.1358412668943562406.stgit@devnote2 Fixes: de462e5f1071 ("bootconfig: Fix to remove bootconfig data from initrd while boot") Signed-off-by: Masami Hiramatsu (Google) Reported-by: Sashiko Closes: https://lore.kernel.org/all/20260910010137.EE0431F000FF@smtp.kernel.org/ Assisted-by: Antigravity:gemini-3.8-flash Cc: Breno Leitao Cc: Christian Brauner Cc: Doug Anderson Cc: Huacai Chen Cc: Marc Rutland Cc: Ryan Roberts Cc: Sang-Heon Jeon Cc: Thomas Weißschuh Cc: Signed-off-by: Andrew Morton --- init/main.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) --- a/init/main.c~bootconfig-fix-integer-overflow-in-initrd-size-check +++ a/init/main.c @@ -277,7 +277,8 @@ static void * __init get_boot_config_fro u8 *hdr; int i; - if (!initrd_end) + if (!initrd_end || initrd_end < initrd_start || + initrd_end - initrd_start < BOOTCONFIG_MAGIC_LEN + 8) return NULL; data = (char *)initrd_end - BOOTCONFIG_MAGIC_LEN; @@ -294,16 +295,26 @@ static void * __init get_boot_config_fro found: hdr = (u8 *)(data - 8); + if ((unsigned long)hdr < initrd_start) + return NULL; + size = get_unaligned_le32(hdr); csum = get_unaligned_le32(hdr + 4); - data = ((void *)hdr) - size; - if ((unsigned long)data < initrd_start) { - pr_err("bootconfig size %d is greater than initrd size %ld\n", + if (size > XBC_DATA_MAX) { + pr_err("bootconfig size %u is greater than max size %d\n", + size, XBC_DATA_MAX); + return NULL; + } + + if (size > ((unsigned long)hdr - initrd_start)) { + pr_err("bootconfig size %u is greater than initrd size %lu\n", size, initrd_end - initrd_start); return NULL; } + data = ((void *)hdr) - size; + if (xbc_calc_checksum(data, size) != csum) { pr_err("bootconfig checksum failed\n"); return NULL; @@ -394,12 +405,6 @@ static void __init setup_boot_config(voi return; } - if (size >= XBC_DATA_MAX) { - pr_err("bootconfig size %ld greater than max size %d\n", - (long)size, XBC_DATA_MAX); - return; - } - ret = xbc_init(data, size, &msg, &pos); if (ret < 0) { if (pos < 0) _ Patches currently in -mm which might be from mhiramat@kernel.org are bootconfig-reject-unexpected-data-after-null-character.patch tools-bootconfig-consolidate-xbc_init-to-error-message-wrapper.patch bootconfig-skip-internal-tree-sanity-checks-in-kernel.patch tools-bootconfig-fix-integer-overflow-and-truncation-in-size-checks.patch bootconfig-fix-integer-overflow-in-initrd-size-check.patch