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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 F271BC2BC11 for ; Tue, 8 Sep 2020 19:08:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B0C7820C09 for ; Tue, 8 Sep 2020 19:08:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599592126; bh=I8d/qW8Ag5Oe9JmXjC+U2NHEEjtcfNhv1BJvHpXPVEc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=AI49/O64fdLOCQslBwxDLYXnpwkvZmF4yTvQN4r4/yb5wLLFN4KwGaM+FyxmzkLOB mtoX3IKrcYuGWFHHlQRatM0La2zZjHOhhTTPHO/a2+2PXJS8TEjZtTWX9Fa7UqOqu2 rktWUl1nnBOoM0wHGUlf0s/RNv51oGAEvlaITE3k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731263AbgIHTIg (ORCPT ); Tue, 8 Sep 2020 15:08:36 -0400 Received: from mail.kernel.org ([198.145.29.99]:52176 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731252AbgIHQG6 (ORCPT ); Tue, 8 Sep 2020 12:06:58 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E344E23E1B; Tue, 8 Sep 2020 15:46:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599580002; bh=I8d/qW8Ag5Oe9JmXjC+U2NHEEjtcfNhv1BJvHpXPVEc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GSPeSubkUbPQ/IFPqCoPejNM7Zaign6aw2BQ6cpVvcavZXKK/m37ecFttVTcprZyO 2zMa74wOAiZHWMAzaPD3qVn58UNWivzFAJqNsQKurwlRAqrAFydorceVnvI+B+HUFO MAyGQXv7DWKauMf8CKW239O0RFQaQUENhPbP3NI0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+b90df26038d1d5d85c97@syzkaller.appspotmail.com, Yang Shi , Andrew Morton , Jan Kara , Linus Torvalds Subject: [PATCH 5.4 121/129] mm: madvise: fix vma user-after-free Date: Tue, 8 Sep 2020 17:26:02 +0200 Message-Id: <20200908152235.894741663@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200908152229.689878733@linuxfoundation.org> References: <20200908152229.689878733@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yang Shi commit 7867fd7cc44e63c6673cd0f8fea155456d34d0de upstream. The syzbot reported the below use-after-free: BUG: KASAN: use-after-free in madvise_willneed mm/madvise.c:293 [inline] BUG: KASAN: use-after-free in madvise_vma mm/madvise.c:942 [inline] BUG: KASAN: use-after-free in do_madvise.part.0+0x1c8b/0x1cf0 mm/madvise.c:1145 Read of size 8 at addr ffff8880a6163eb0 by task syz-executor.0/9996 CPU: 0 PID: 9996 Comm: syz-executor.0 Not tainted 5.9.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xae/0x497 mm/kasan/report.c:383 __kasan_report mm/kasan/report.c:513 [inline] kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530 madvise_willneed mm/madvise.c:293 [inline] madvise_vma mm/madvise.c:942 [inline] do_madvise.part.0+0x1c8b/0x1cf0 mm/madvise.c:1145 do_madvise mm/madvise.c:1169 [inline] __do_sys_madvise mm/madvise.c:1171 [inline] __se_sys_madvise mm/madvise.c:1169 [inline] __x64_sys_madvise+0xd9/0x110 mm/madvise.c:1169 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Allocated by task 9992: kmem_cache_alloc+0x138/0x3a0 mm/slab.c:3482 vm_area_alloc+0x1c/0x110 kernel/fork.c:347 mmap_region+0x8e5/0x1780 mm/mmap.c:1743 do_mmap+0xcf9/0x11d0 mm/mmap.c:1545 vm_mmap_pgoff+0x195/0x200 mm/util.c:506 ksys_mmap_pgoff+0x43a/0x560 mm/mmap.c:1596 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Freed by task 9992: kmem_cache_free.part.0+0x67/0x1f0 mm/slab.c:3693 remove_vma+0x132/0x170 mm/mmap.c:184 remove_vma_list mm/mmap.c:2613 [inline] __do_munmap+0x743/0x1170 mm/mmap.c:2869 do_munmap mm/mmap.c:2877 [inline] mmap_region+0x257/0x1780 mm/mmap.c:1716 do_mmap+0xcf9/0x11d0 mm/mmap.c:1545 vm_mmap_pgoff+0x195/0x200 mm/util.c:506 ksys_mmap_pgoff+0x43a/0x560 mm/mmap.c:1596 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 It is because vma is accessed after releasing mmap_lock, but someone else acquired the mmap_lock and the vma is gone. Releasing mmap_lock after accessing vma should fix the problem. Fixes: 692fe62433d4c ("mm: Handle MADV_WILLNEED through vfs_fadvise()") Reported-by: syzbot+b90df26038d1d5d85c97@syzkaller.appspotmail.com Signed-off-by: Yang Shi Signed-off-by: Andrew Morton Reviewed-by: Andrew Morton Reviewed-by: Jan Kara Cc: [5.4+] Link: https://lkml.kernel.org/r/20200816141204.162624-1-shy828301@gmail.com Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/madvise.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/madvise.c +++ b/mm/madvise.c @@ -288,9 +288,9 @@ static long madvise_willneed(struct vm_a */ *prev = NULL; /* tell sys_madvise we drop mmap_sem */ get_file(file); - up_read(¤t->mm->mmap_sem); offset = (loff_t)(start - vma->vm_start) + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); + up_read(¤t->mm->mmap_sem); vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED); fput(file); down_read(¤t->mm->mmap_sem);