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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 592C4C3A5A2 for ; Sun, 22 Sep 2019 13:19:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2FDC1208C0 for ; Sun, 22 Sep 2019 13:19:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569158385; bh=uXJA1WEPwLkYZYaYcHaGm0191fkWYeUnl7ENiDbfUJU=; h=Date:From:To:Cc:Subject:List-ID:From; b=vZDdHfeCn4fngD2dsCWP5ge004krTs5d7xlmBeN0H/NMBJgkOR7m/jYcI+Sl6bv2C 6LZ1ezBlAlo8bh/wQwYCryYcBOjYXdVHgkpQgLLak6QZcIROeh6kX+C7anu5KHvljP kf+roJA8d1hkzxRX+SSRZ7RjBL3VtjxHhV/Jnej0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728902AbfIVNTo (ORCPT ); Sun, 22 Sep 2019 09:19:44 -0400 Received: from mail-qt1-f196.google.com ([209.85.160.196]:42668 "EHLO mail-qt1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728764AbfIVNTn (ORCPT ); Sun, 22 Sep 2019 09:19:43 -0400 Received: by mail-qt1-f196.google.com with SMTP id w14so9684916qto.9; Sun, 22 Sep 2019 06:19:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:mime-version :content-disposition:user-agent; bh=uNO9UuhB7M6CiHUosVbc5HEwCkGc2F4p4dUUxU7OnMc=; b=itpkqRQ470AT0lxjFU6H1qesOezH2PykkOk8ndMezitG9w40XDq6VJxR+lqRz725JD Tt4+jzcyvcpeAswV0svLaY9Kq6dXmTMlHTGdA0lZ/Rt2xpDQ3Ei3AV5YXAbiYgB2Chi4 jYLbwZyzYoh+AkIqhy82hFHhym1+ZzT5mjqk6W3CkFsxnPc44QytwTjXzLEYSxo0gXD+ b+GOM4hsikKQtDgorfRcuc6IQ/oNTAcWtVove+2txD43As2MD7yPvLfIOat0cbxwZyxb hrdgVqf6Ca9O+vB2RZW/Ya5PPvBNXEbzDa2rPIE01TQ4CgPZ8WkTjHb0kv/7Wdf0JbjV +aEg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :mime-version:content-disposition:user-agent; bh=uNO9UuhB7M6CiHUosVbc5HEwCkGc2F4p4dUUxU7OnMc=; b=OPsTsh/5WKePaR+mP1z62ViCHSSKTGU1sm0v6XBWd0OXMmzcTBvlXeKu1rwygeQRyy g7n12g6nhIVq/5LPIt5UyywGQIQ1Rr1eiLLtoLkECAtI5+Klf65FQXmV0RrR3Jcd3f2G t29YsNEkHFJeVPqSRVpyAGBYKfVF52dQx1RtZoTkk3x7xKJSfHQ2HNvtNByDacII2lGk xT1AdNwBOzfzYbjC2WgzvVTGAjpM+5WlvuKHjVLsCApohR6h0m0Wk+wvq/t3tLRf64ZZ XQqxSEwMdGsp/MdIj1If8/9i7TtGhTqGxc88ckLv0qYbEF0ZoKdMdXAFUMesmN2OBN6r HIWQ== X-Gm-Message-State: APjAAAUMpIksxg1fOSZ80hO8PYuXadO/YoBWeTxbWXRtNiwMIjzpMnfC ryoyRHJ2K5Xyc1zRE0Mga0w= X-Google-Smtp-Source: APXvYqzQE7aMzabm+ubBc3vvlI/+LrGJVWqwJUXtLS3LnJXSQfAaKw/kU5+qkfLDOpZP1CbA796Kyw== X-Received: by 2002:ad4:5552:: with SMTP id v18mr20777945qvy.185.1569158380829; Sun, 22 Sep 2019 06:19:40 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::34ed]) by smtp.gmail.com with ESMTPSA id d133sm4414760qkg.31.2019.09.22.06.19.38 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 22 Sep 2019 06:19:39 -0700 (PDT) Date: Sun, 22 Sep 2019 06:19:36 -0700 From: Tejun Heo To: Miklos Szeredi Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] FUSE: fix beyond-end-of-page access in fuse_parse_cache() Message-ID: <20190922131936.GE2233839@devbig004.ftw2.facebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org With DEBUG_PAGEALLOC on, the following triggers. BUG: unable to handle page fault for address: ffff88859367c000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 3001067 P4D 3001067 PUD 406d3a8067 PMD 406d30c067 PTE 800ffffa6c983060 Oops: 0000 [#1] SMP DEBUG_PAGEALLOC CPU: 38 PID: 3110657 Comm: python2.7 RIP: 0010:fuse_readdir+0x88f/0xe7a [fuse] Code: 49 8b 4d 08 49 39 4e 60 0f 84 44 04 00 00 48 8b 43 08 43 8d 1c 3c 4d 01 7e 68 49 89 dc 48 03 5c 24 38 49 89 46 60 8b 44 24 30 <8b> 4b 10 44 29 e0 48 89 ca 48 83 c1 1f 48 83 e1 f8 83 f8 17 49 89 RSP: 0018:ffffc90035edbde0 EFLAGS: 00010286 RAX: 0000000000001000 RBX: ffff88859367bff0 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff88859367bfed RDI: 0000000000920907 RBP: ffffc90035edbe90 R08: 000000000000014b R09: 0000000000000004 R10: ffff88859367b000 R11: 0000000000000000 R12: 0000000000000ff0 R13: ffffc90035edbee0 R14: ffff889fb8546180 R15: 0000000000000020 FS: 00007f80b5f4a740(0000) GS:ffff889fffa00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff88859367c000 CR3: 0000001c170c2001 CR4: 00000000003606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: iterate_dir+0x122/0x180 __x64_sys_getdents+0xa6/0x140 do_syscall_64+0x42/0x100 entry_SYSCALL_64_after_hwframe+0x44/0xa9 faddr2line says fuse_readdir+0x88f/0x38fc9b: fuse_parse_cache at /builddir/build/BUILD/kernel-5.2.9-1992_g2c63931edbb0/fs/fuse/readdir.c:375 (inlined by) fuse_readdir_cached at /builddir/build/BUILD/kernel-5.2.9-1992_g2c63931edbb0/fs/fuse/readdir.c:524 (inlined by) fuse_readdir at /builddir/build/BUILD/kernel-5.2.9-1992_g2c63931edbb0/fs/fuse/readdir.c:562 It's in fuse_parse_cache(). %rbx (ffff88859367bff0) is fuse_dirent pointer - addr + offset. FUSE_DIRENT_SIZE() is trying to dereference namelen off of it but that derefs into the next page which is disabled by pagealloc debug causing a PF. This is caused by dirent->namelen being accessed before ensuring that there's enough bytes in the page for the dirent. Fix it by pushing down reclen calculation. Signed-off-by: Tejun Heo Fixes: 5d7bc7e8680c ("fuse: allow using readdir cache") Cc: stable@vger.kernel.org # v4.20+ --- fs/fuse/readdir.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c index 574d03f8a573..b2da3de6a78e 100644 --- a/fs/fuse/readdir.c +++ b/fs/fuse/readdir.c @@ -372,11 +372,13 @@ static enum fuse_parse_result fuse_parse_cache(struct fuse_file *ff, for (;;) { struct fuse_dirent *dirent = addr + offset; unsigned int nbytes = size - offset; - size_t reclen = FUSE_DIRENT_SIZE(dirent); + size_t reclen; if (nbytes < FUSE_NAME_OFFSET || !dirent->namelen) break; + reclen = FUSE_DIRENT_SIZE(dirent); /* derefs ->namelen */ + if (WARN_ON(dirent->namelen > FUSE_NAME_MAX)) return FOUND_ERR; if (WARN_ON(reclen > nbytes))