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 X-Spam-Level: X-Spam-Status: No, score=-12.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37521C43461 for ; Wed, 16 Sep 2020 09:09:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 087582087D for ; Wed, 16 Sep 2020 09:09:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726630AbgIPJJN (ORCPT ); Wed, 16 Sep 2020 05:09:13 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:12304 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726129AbgIPJJK (ORCPT ); Wed, 16 Sep 2020 05:09:10 -0400 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 787E2330D12FE261413A; Wed, 16 Sep 2020 17:09:00 +0800 (CST) Received: from huawei.com (10.175.104.175) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.487.0; Wed, 16 Sep 2020 17:08:51 +0800 From: Miaohe Lin To: CC: , , Subject: [PATCH] mm: mmap: Fix general protection fault in unlink_file_vma() Date: Wed, 16 Sep 2020 05:07:33 -0400 Message-ID: <20200916090733.31427-1-linmiaohe@huawei.com> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.104.175] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The syzbot reported the below general protection fault: general protection fault, probably for non-canonical address 0xe00eeaee0000003b: 0000 [#1] PREEMPT SMP KASAN KASAN: maybe wild-memory-access in range [0x00777770000001d8-0x00777770000001df] CPU: 1 PID: 10488 Comm: syz-executor721 Not tainted 5.9.0-rc3-syzkaller #0 RIP: 0010:unlink_file_vma+0x57/0xb0 mm/mmap.c:164 Code: 4c 8b a5 a0 00 00 00 4d 85 e4 74 4e e8 92 d7 cd ff 49 8d bc 24 d8 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 3d 4d 8b b4 24 d8 01 00 00 4d 8d 6e 78 4c 89 ef e8 RSP: 0018:ffffc9000ac0f9b0 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: ffff88800010ceb0 RCX: ffffffff81592421 RDX: 000eeeee0000003b RSI: ffffffff81a6736e RDI: 00777770000001d8 RBP: ffff88800010ceb0 R08: 0000000000000001 R09: ffff88801291a50f R10: ffffed10025234a1 R11: 0000000000000001 R12: 0077777000000000 R13: 00007f1eea0da000 R14: 00007f1eea0d9000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1eea11a9d0 CR3: 000000000007e000 CR4: 00000000001506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: free_pgtables+0x1b3/0x2f0 mm/memory.c:415 exit_mmap+0x2c0/0x530 mm/mmap.c:3184 __mmput+0x122/0x470 kernel/fork.c:1076 mmput+0x53/0x60 kernel/fork.c:1097 exit_mm kernel/exit.c:483 [inline] do_exit+0xa8b/0x29f0 kernel/exit.c:793 do_group_exit+0x125/0x310 kernel/exit.c:903 get_signal+0x428/0x1f00 kernel/signal.c:2757 arch_do_signal+0x82/0x2520 arch/x86/kernel/signal.c:811 exit_to_user_mode_loop kernel/entry/common.c:136 [inline] exit_to_user_mode_prepare+0x1ae/0x200 kernel/entry/common.c:167 syscall_exit_to_user_mode+0x7e/0x2e0 kernel/entry/common.c:242 entry_SYSCALL_64_after_hwframe+0x44/0xa9 It's because the ->mmap() callback can change vma->vm_file and fput the original file. But the commit d70cec898324 ("mm: mmap: merge vma after call_mmap() if possible") failed to catch this case and always fput() the original file, hence add an extra fput(). [ Thanks Hillf for pointing this extra fput() out. ] Fixes: d70cec898324 ("mm: mmap: merge vma after call_mmap() if possible") Reported-by: syzbot+c5d5a51dcbb558ca0cb5@syzkaller.appspotmail.com Signed-off-by: Miaohe Lin --- mm/mmap.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/mm/mmap.c b/mm/mmap.c index e3a1c1b48909..37c985850dc6 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1815,7 +1815,11 @@ unsigned long mmap_region(struct file *file, unsigned long addr, merge = vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags, NULL, vma->vm_file, vma->vm_pgoff, NULL, NULL_VM_UFFD_CTX); if (merge) { - fput(file); + /* ->mmap() can change vma->vm_file and fput the original file. So + * fput the vma->vm_file here or we would add an extra fput for file + * and cause general protection fault ultimately. + */ + fput(vma->vm_file); vm_area_free(vma); vma = merge; /* Update vm_flags and possible addr to pick up the change. We don't -- 2.19.1