From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5A74FC433FE for ; Fri, 21 Oct 2022 20:45:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229501AbiJUUo4 (ORCPT ); Fri, 21 Oct 2022 16:44:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230146AbiJUUof (ORCPT ); Fri, 21 Oct 2022 16:44:35 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A7C3E24E384 for ; Fri, 21 Oct 2022 13:44:16 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id C4761B82A2F for ; Fri, 21 Oct 2022 20:42:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7DB1EC433D6; Fri, 21 Oct 2022 20:42:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1666384978; bh=MlEtcdML/U1VLppbRWrYbmJ7erk5bgaeOCwd9fErOqg=; h=Date:To:From:Subject:From; b=x8rdJuZV0TKmBk0S8L9j9dkVJ4cgsQkifpldKhri/S/t8nszCXFixBwdcTamkFjpr w/aLeWxzgGxMasbn1YQhFmfMxW1K3oIAU639aW4/9/VKQNW1DtgQ0bJRyU4oP8ys7D EX02Qj8qatBSXg+mb8J6ce+npvB2VcFbkwGOdigY= Date: Fri, 21 Oct 2022 13:42:57 -0700 To: mm-commits@vger.kernel.org, songmuchun@bytedance.com, raven@themaw.net, mike.kravetz@oracle.com, yin31149@gmail.com, akpm@linux-foundation.org From: Andrew Morton Subject: + hugetlbfs-fix-null-ptr-deref-in-hugetlbfs_parse_param.patch added to mm-unstable branch Message-Id: <20221021204258.7DB1EC433D6@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: hugetlbfs: fix null-ptr-deref in hugetlbfs_parse_param() has been added to the -mm mm-unstable branch. Its filename is hugetlbfs-fix-null-ptr-deref-in-hugetlbfs_parse_param.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/hugetlbfs-fix-null-ptr-deref-in-hugetlbfs_parse_param.patch This patch will later appear in the mm-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 the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Hawkins Jiawei Subject: hugetlbfs: fix null-ptr-deref in hugetlbfs_parse_param() Date: Fri, 21 Oct 2022 07:16:08 +0800 Syzkaller reports a null-ptr-deref bug as follows: ====================================================== KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:hugetlbfs_parse_param+0x1dd/0x8e0 fs/hugetlbfs/inode.c:1380 [...] Call Trace: vfs_parse_fs_param fs/fs_context.c:148 [inline] vfs_parse_fs_param+0x1f9/0x3c0 fs/fs_context.c:129 vfs_parse_fs_string+0xdb/0x170 fs/fs_context.c:191 generic_parse_monolithic+0x16f/0x1f0 fs/fs_context.c:231 do_new_mount fs/namespace.c:3036 [inline] path_mount+0x12de/0x1e20 fs/namespace.c:3370 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline] __se_sys_mount fs/namespace.c:3568 [inline] __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd [...] ====================================================== According to commit "vfs: parse: deal with zero length string value", kernel will set the param->string to null pointer in vfs_parse_fs_string() if fs string has zero length. Yet the problem is that, hugetlbfs_parse_param() will dereference the param->string, without checking whether it is a null pointer. To be more specific, if hugetlbfs_parse_param() parses an illegal mount parameter, such as "size=,", kernel will constructs struct fs_parameter with null pointer in vfs_parse_fs_string(), then passes this struct fs_parameter to hugetlbfs_parse_param(), which triggers the above null-ptr-deref bug. This patch solves it by adding sanity check on param->string in hugetlbfs_parse_param(). Link: https://lkml.kernel.org/r/20221020231609.4810-1-yin31149@gmail.com Reported-by: syzbot+a3e6acd85ded5c16a709@syzkaller.appspotmail.com Tested-by: syzbot+a3e6acd85ded5c16a709@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/0000000000005ad00405eb7148c6@google.com/ Signed-off-by: Hawkins Jiawei Cc: Hawkins Jiawei Cc: Mike Kravetz Cc: Muchun Song Cc: Ian Kent Signed-off-by: Andrew Morton --- fs/hugetlbfs/inode.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/fs/hugetlbfs/inode.c~hugetlbfs-fix-null-ptr-deref-in-hugetlbfs_parse_param +++ a/fs/hugetlbfs/inode.c @@ -1377,7 +1377,7 @@ static int hugetlbfs_parse_param(struct case Opt_size: /* memparse() will accept a K/M/G without a digit */ - if (!isdigit(param->string[0])) + if (!param->string || !isdigit(param->string[0])) goto bad_val; ctx->max_size_opt = memparse(param->string, &rest); ctx->max_val_type = SIZE_STD; @@ -1387,7 +1387,7 @@ static int hugetlbfs_parse_param(struct case Opt_nr_inodes: /* memparse() will accept a K/M/G without a digit */ - if (!isdigit(param->string[0])) + if (!param->string || !isdigit(param->string[0])) goto bad_val; ctx->nr_inodes = memparse(param->string, &rest); return 0; @@ -1403,7 +1403,7 @@ static int hugetlbfs_parse_param(struct case Opt_min_size: /* memparse() will accept a K/M/G without a digit */ - if (!isdigit(param->string[0])) + if (!param->string || !isdigit(param->string[0])) goto bad_val; ctx->min_size_opt = memparse(param->string, &rest); ctx->min_val_type = SIZE_STD; _ Patches currently in -mm which might be from yin31149@gmail.com are hugetlbfs-fix-null-ptr-deref-in-hugetlbfs_parse_param.patch