From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out28-101.mail.aliyun.com (out28-101.mail.aliyun.com [115.124.28.101]) (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 50A553B47CD; Wed, 16 Sep 2026 17:48:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.28.101 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789580890; cv=none; b=PCF59AkSf8rj7vtjkWJae3hHwd6BST4HZUpZj/f4SAM3OTepE0xJmvs0RWjZ6CoaZ4ERdzLzkGQNkOJv5p4X/0kVVG/VZSxXjEpilYT6HhU44UZhHDpYHcv0xGUyqEnkvCjGI8v1Qoc+aIe8X4NPdAZEW5UzeorK18t0An9ieQQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789580890; c=relaxed/simple; bh=5SVan4TztOsht+PNjOT1U3SsgeW2aiaq0MZz1YZ/ldo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=EnzvCYNNF1590trwECk6SqXjG2gBHeX9RtuWVYp86/r765K5vMNmZg4jjhVVEIbvfo092UzOMoWkJuz7z+3CiW8EkbA7IvqwzaWci/GU3XbCKo3bEWr9ZRJXks+j37xfkQRVZR+393OccK4l5ebU2WNv4s448jY1MTq7+VIyNK8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xiaopeng.com; spf=pass smtp.mailfrom=xiaopeng.com; dkim=pass (1024-bit key) header.d=xiaopeng.com header.i=@xiaopeng.com header.b=SIQZAsbz; arc=none smtp.client-ip=115.124.28.101 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xiaopeng.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=xiaopeng.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=xiaopeng.com header.i=@xiaopeng.com header.b="SIQZAsbz" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=xiaopeng.com; s=default; t=1789580877; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=azJubOKUIjMTBXlSrVQ1zbXf17NBQi6Q2PS0BXsTCSo=; b=SIQZAsbzYzt95asFNfnLuwjwhOJlODvEe9e8MfVTEDNVERppOaD0CxxVvTzW6yP+G1RyRvnA/GkNRruc+gFqYzKimBZhmvyhNqmyilI3YQudKqsmK/PgWGA+tMO1vekr7LRd8HtKXsz197uZbsXSXcZjLwIs4McWztb5nWsMU4A= X-Alimail-AntiSpam:AC=CONTINUE;BC=0.04436835|-1;CH=green;DM=|CONTINUE|false|;DS=CONTINUE|ham_regular_dialog|0.0354802-0.00586873-0.958651;FP=5742756620908168539|0|0|0|0|-1|-1|-1;HT=maildocker-contentspam011083013073;MF=fangxy@xiaopeng.com;NM=1;PH=DS;RN=10;RT=10;SR=0;TI=SMTPD_---.jFIg.VU_1789580876; Received: from localhost.localdomain(mailfrom:fangxy@xiaopeng.com fp:SMTPD_---.jFIg.VU_1789580876 cluster:ay29) by smtp.aliyun-inc.com; Thu, 17 Sep 2026 01:47:57 +0800 From: Fang Xieyan To: mcgrof@kernel.org, petr.pavlu@suse.com, da.gomez@kernel.org, samitolvanen@google.com, atomlin@atomlin.com Cc: mmaurer@google.com, masahiroy@kernel.org, linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH 2/2] module: Validate the __version_ext_names section offset Date: Thu, 17 Sep 2026 01:47:53 +0800 Message-ID: <20260916174753.14870-3-fangxy@xiaopeng.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260916174753.14870-1-fangxy@xiaopeng.com> References: <20260916174753.14870-1-fangxy@xiaopeng.com> Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit elf_validity_check_sectionheaders() validates the size and offset of every section, unless its type is SHT_NULL or SHT_NOBITS: switch (shdr->sh_type) { case SHT_NULL: case SHT_NOBITS: /* No contents, offset/size don't mean anything */ continue; default: err = validate_section_offset(info, shdr); elf_validity_cache_index_versions() then reads the extended version names by their sh_offset, without checking that the section holds data: if (vers_ext_crc) { crc_count = info->sechdrs[vers_ext_crc].sh_size / sizeof(u32); name = (void *)info->hdr + info->sechdrs[vers_ext_name].sh_offset; remaining_len = info->sechdrs[vers_ext_name].sh_size; while (crc_count--) { name_size = strnlen(name, remaining_len) + 1; A __version_ext_names section of type SHT_NOBITS reaches here with an unvalidated sh_offset, so the name lookup reads past the in-memory copy of the module: BUG: KASAN: vmalloc-out-of-bounds in strnlen+0x73/0x80 Read of size 1 at addr ffa00000005534ff by task insmod/79 ... strnlen+0x73/0x80 load_module+0xef6/0x8600 The buggy address belongs to a 43-page vmalloc region starting at 0xffa0000000529000 allocated at kernel_read_file+0x7b4/0x9f0 A real __version_ext_names section is SHT_PROGBITS and has already passed validate_section_offset(), so this only rejects a SHT_NOBITS section, which holds no names to read. Validate the offset before the dereference. Fixes: 54ac1ac8edeb ("modules: Support extended MODVERSIONS info") Cc: stable@vger.kernel.org Assisted-by: Hawkeye:GLM-5.3-flash Assisted-by: Qoder:Qwen3.8-Max Signed-off-by: Fang Xieyan --- Found in the same review as patch 1/2. elf_validity_check_sectionheaders() exempts SHT_NOBITS from validate_section_offset(), and elf_validity_cache_index_versions() then dereferences the __version_ext_names section as hdr + sh_offset without re-checking it, so a section of that name and type SHT_NOBITS carries an unvalidated offset into the extended version name walk. This patch stands on its own; it does not depend on patch 1/2. Reproducer: build a .ko that carries __version_ext_crcs and a __version_ext_names section of type SHT_NOBITS whose sh_offset points past the end of the module image. insmod it. Before the change the name walk reads out of bounds; after it validate_section_offset() rejects the section and insmod fails with -ENOEXEC (rc=8, "invalid module format"), which is what a module with a malformed version section should do. Both cases ran on 704340f1cd0d (v7.3-rc4): x86_64 defconfig plus CONFIG_KASAN_GENERIC and CONFIG_KASAN_VMALLOC, gcc 13.2.0, QEMU under TCG. The unpatched and patched kernels are built from byte-identical .config files and differ only by this patch. The same vermagic caveat as patch 1/2 applies: LOCALVERSION is pinned so the patched kernel's release string matches the payload, and the loader reaches the version walk instead of stopping at the version magic check. kernel/module/main.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/kernel/module/main.c b/kernel/module/main.c index e36bfe4..adaaaca 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -2296,6 +2296,16 @@ static int elf_validity_cache_index_versions(struct load_info *info, int flags) * number of entries in every section. */ if (vers_ext_crc) { + /* + * The name section is walked by its sh_offset and sh_size + * below. elf_validity_check_sectionheaders() exempts SHT_NOBITS + * sections from validate_section_offset(), so a __version_ext_names + * section of that type reaches here with an unvalidated sh_offset. + * Bound it before dereferencing hdr + sh_offset. + */ + if (validate_section_offset(info, &info->sechdrs[vers_ext_name])) + return -ENOEXEC; + crc_count = info->sechdrs[vers_ext_crc].sh_size / sizeof(u32); name = (void *)info->hdr + info->sechdrs[vers_ext_name].sh_offset; -- 2.50.1 (Apple Git-155)