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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 8A842C43381 for ; Wed, 13 Mar 2019 09:41:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 563D52173C for ; Wed, 13 Mar 2019 09:41:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727276AbfCMJlM (ORCPT ); Wed, 13 Mar 2019 05:41:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:46722 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726163AbfCMJlM (ORCPT ); Wed, 13 Mar 2019 05:41:12 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 3DF41AC18; Wed, 13 Mar 2019 09:41:10 +0000 (UTC) Subject: Re: [PATCH 6/6] btrfs: inode: Verify inode mode to avoid NULL pointer dereference To: Qu Wenruo , linux-btrfs@vger.kernel.org Cc: Yoon Jungyeon References: <20190313085511.23540-1-wqu@suse.com> <20190313085511.23540-7-wqu@suse.com> From: Nikolay Borisov Openpgp: preference=signencrypt Autocrypt: addr=nborisov@suse.com; prefer-encrypt=mutual; keydata= mQINBFiKBz4BEADNHZmqwhuN6EAzXj9SpPpH/nSSP8YgfwoOqwrP+JR4pIqRK0AWWeWCSwmZ T7g+RbfPFlmQp+EwFWOtABXlKC54zgSf+uulGwx5JAUFVUIRBmnHOYi/lUiE0yhpnb1KCA7f u/W+DkwGerXqhhe9TvQoGwgCKNfzFPZoM+gZrm+kWv03QLUCr210n4cwaCPJ0Nr9Z3c582xc bCUVbsjt7BN0CFa2BByulrx5xD9sDAYIqfLCcZetAqsTRGxM7LD0kh5WlKzOeAXj5r8DOrU2 GdZS33uKZI/kZJZVytSmZpswDsKhnGzRN1BANGP8sC+WD4eRXajOmNh2HL4P+meO1TlM3GLl EQd2shHFY0qjEo7wxKZI1RyZZ5AgJnSmehrPCyuIyVY210CbMaIKHUIsTqRgY5GaNME24w7h TyyVCy2qAM8fLJ4Vw5bycM/u5xfWm7gyTb9V1TkZ3o1MTrEsrcqFiRrBY94Rs0oQkZvunqia c+NprYSaOG1Cta14o94eMH271Kka/reEwSZkC7T+o9hZ4zi2CcLcY0DXj0qdId7vUKSJjEep c++s8ncFekh1MPhkOgNj8pk17OAESanmDwksmzh1j12lgA5lTFPrJeRNu6/isC2zyZhTwMWs k3LkcTa8ZXxh0RfWAqgx/ogKPk4ZxOXQEZetkEyTFghbRH2BIwARAQABtCNOaWtvbGF5IEJv cmlzb3YgPG5ib3Jpc292QHN1c2UuY29tPokCOAQTAQIAIgUCWIo48QIbAwYLCQgHAwIGFQgC CQoLBBYCAwECHgECF4AACgkQcb6CRuU/KFc0eg/9GLD3wTQz9iZHMFbjiqTCitD7B6dTLV1C ddZVlC8Hm/TophPts1bWZORAmYIihHHI1EIF19+bfIr46pvfTu0yFrJDLOADMDH+Ufzsfy2v HSqqWV/nOSWGXzh8bgg/ncLwrIdEwBQBN9SDS6aqsglagvwFD91UCg/TshLlRxD5BOnuzfzI Leyx2c6YmH7Oa1R4MX9Jo79SaKwdHt2yRN3SochVtxCyafDlZsE/efp21pMiaK1HoCOZTBp5 VzrIP85GATh18pN7YR9CuPxxN0V6IzT7IlhS4Jgj0NXh6vi1DlmKspr+FOevu4RVXqqcNTSS E2rycB2v6cttH21UUdu/0FtMBKh+rv8+yD49FxMYnTi1jwVzr208vDdRU2v7Ij/TxYt/v4O8 V+jNRKy5Fevca/1xroQBICXsNoFLr10X5IjmhAhqIH8Atpz/89ItS3+HWuE4BHB6RRLM0gy8 T7rN6ja+KegOGikp/VTwBlszhvfLhyoyjXI44Tf3oLSFM+8+qG3B7MNBHOt60CQlMkq0fGXd mm4xENl/SSeHsiomdveeq7cNGpHi6i6ntZK33XJLwvyf00PD7tip/GUj0Dic/ZUsoPSTF/mG EpuQiUZs8X2xjK/AS/l3wa4Kz2tlcOKSKpIpna7V1+CMNkNzaCOlbv7QwprAerKYywPCoOSC 7P25Ag0EWIoHPgEQAMiUqvRBZNvPvki34O/dcTodvLSyOmK/MMBDrzN8Cnk302XfnGlW/YAQ csMWISKKSpStc6tmD+2Y0z9WjyRqFr3EGfH1RXSv9Z1vmfPzU42jsdZn667UxrRcVQXUgoKg QYx055Q2FdUeaZSaivoIBD9WtJq/66UPXRRr4H/+Y5FaUZx+gWNGmBT6a0S/GQnHb9g3nonD jmDKGw+YO4P6aEMxyy3k9PstaoiyBXnzQASzdOi39BgWQuZfIQjN0aW+Dm8kOAfT5i/yk59h VV6v3NLHBjHVw9kHli3jwvsizIX9X2W8tb1SefaVxqvqO1132AO8V9CbE1DcVT8fzICvGi42 FoV/k0QOGwq+LmLf0t04Q0csEl+h69ZcqeBSQcIMm/Ir+NorfCr6HjrB6lW7giBkQl6hhomn l1mtDP6MTdbyYzEiBFcwQD4terc7S/8ELRRybWQHQp7sxQM/Lnuhs77MgY/e6c5AVWnMKd/z MKm4ru7A8+8gdHeydrRQSWDaVbfy3Hup0Ia76J9FaolnjB8YLUOJPdhI2vbvNCQ2ipxw3Y3c KhVIpGYqwdvFIiz0Fej7wnJICIrpJs/+XLQHyqcmERn3s/iWwBpeogrx2Lf8AGezqnv9woq7 OSoWlwXDJiUdaqPEB/HmGfqoRRN20jx+OOvuaBMPAPb+aKJyle8zABEBAAGJAh8EGAECAAkF AliKBz4CGwwACgkQcb6CRuU/KFdacg/+M3V3Ti9JYZEiIyVhqs+yHb6NMI1R0kkAmzsGQ1jU zSQUz9AVMR6T7v2fIETTT/f5Oout0+Hi9cY8uLpk8CWno9V9eR/B7Ifs2pAA8lh2nW43FFwp IDiSuDbH6oTLmiGCB206IvSuaQCp1fed8U6yuqGFcnf0ZpJm/sILG2ECdFK9RYnMIaeqlNQm iZicBY2lmlYFBEaMXHoy+K7nbOuizPWdUKoKHq+tmZ3iA+qL5s6Qlm4trH28/fPpFuOmgP8P K+7LpYLNSl1oQUr+WlqilPAuLcCo5Vdl7M7VFLMq4xxY/dY99aZx0ZJQYFx0w/6UkbDdFLzN upT7NIN68lZRucImffiWyN7CjH23X3Tni8bS9ubo7OON68NbPz1YIaYaHmnVQCjDyDXkQoKC R82Vf9mf5slj0Vlpf+/Wpsv/TH8X32ajva37oEQTkWNMsDxyw3aPSps6MaMafcN7k60y2Wk/ TCiLsRHFfMHFY6/lq/c0ZdOsGjgpIK0G0z6et9YU6MaPuKwNY4kBdjPNBwHreucrQVUdqRRm RcxmGC6ohvpqVGfhT48ZPZKZEWM+tZky0mO7bhZYxMXyVjBn4EoNTsXy1et9Y1dU3HVJ8fod 5UqrNrzIQFbdeM0/JqSLrtlTcXKJ7cYFa9ZM2AP7UIN9n1UWxq+OPY9YMOewVfYtL8M= Message-ID: Date: Wed, 13 Mar 2019 11:41:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190313085511.23540-7-wqu@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 13.03.19 г. 10:55 ч., Qu Wenruo wrote: > [BUG] > When access a file on a crafted image, btrfs can crash in block layer: > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 > PGD 136501067 P4D 136501067 PUD 124519067 PMD 0 > CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.0.0-rc8-default #252 > RIP: 0010:end_bio_extent_readpage+0x144/0x700 > Call Trace: > > blk_update_request+0x8f/0x350 > blk_mq_end_request+0x1a/0x120 > blk_done_softirq+0x99/0xc0 > __do_softirq+0xc7/0x467 > irq_exit+0xd1/0xe0 > call_function_single_interrupt+0xf/0x20 > > RIP: 0010:default_idle+0x1e/0x170 > > [CAUSE] > The crafted image has a pretty tricky corruption, the INODE_ITEM has a > different type against its parent dir: > item 20 key (268 INODE_ITEM 0) itemoff 2808 itemsize 160 > generation 13 transid 13 size 1048576 nbytes 1048576 > block group 0 mode 121644 links 1 uid 0 gid 0 rdev 0 > sequence 9 flags 0x0(none) > > This mode number 0120000 means it's a soft link. > > But the dir item think it's still a regular file: > item 8 key (264 DIR_INDEX 5) itemoff 3707 itemsize 32 > location key (268 INODE_ITEM 0) type FILE > transid 13 data_len 0 name_len 2 > name: f4 > item 40 key (264 DIR_ITEM 51821248) itemoff 1573 itemsize 32 > location key (268 INODE_ITEM 0) type FILE > transid 13 data_len 0 name_len 2 > name: f4 > > For btrfs symlink, we don't set BTRFS_I(inode)->io_tree.ops and leave > it empty, as symlink is only designed to have inlined extent, all > handled by tree block read. > Thus no need to trigger btrfs_submit_bio_hook() for inline file extent. > > However for end_bio_extent_readpage() it expects tree->ops populated, as > it's reading regular data extent. > This causes NULL pointer dereference. > > [FIX] > This patch fixes the problem by 2 directions: > - Verify inode mode against its dir item when looking up inode > So in btrfs_lookup_dentry() if we find inode mode mismatch with dir > item, we error out so that corrupted inode will not be access. > > - Verify inode mode when getting extent mapping > Only regular file should have regular or preallocated extent. > If we found regular/preallocated file extent for soft link or > whatever, we error out before we submit read bio. > > With this fix that crafted image can be rejected gracefully: > BTRFS critical (device loop0): inode mode mismatch with dir: inode mode=0121644 btrfs type=7 dir type=1 > > Reported-by: Yoon Jungyeon > Link: https://bugzilla.kernel.org/show_bug.cgi?id=202763 > Signed-off-by: Qu Wenruo Reviewed-by: Nikolay Borisov > --- > fs/btrfs/inode.c | 38 ++++++++++++++++++++++++++++-------- > fs/btrfs/tests/inode-tests.c | 1 + > 2 files changed, 31 insertions(+), 8 deletions(-) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 5c349667c761..4ced641aaa8e 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -5396,12 +5396,13 @@ void btrfs_evict_inode(struct inode *inode) > } > > /* > - * this returns the key found in the dir entry in the location pointer. > + * this returns the key found in the dir entry in the location pointer, > + * fill @type with BTRFS_FT_*, and return 0. > * If no dir entries were found, returns -ENOENT. > * If found a corrupted location in dir entry, returns -EUCLEAN. > */ > static int btrfs_inode_by_name(struct inode *dir, struct dentry *dentry, > - struct btrfs_key *location) > + struct btrfs_key *location, u8 *type) > { > const char *name = dentry->d_name.name; > int namelen = dentry->d_name.len; > @@ -5430,6 +5431,8 @@ static int btrfs_inode_by_name(struct inode *dir, struct dentry *dentry, > __func__, name, btrfs_ino(BTRFS_I(dir)), > location->objectid, location->type, location->offset); > } > + if (!ret) > + *type = btrfs_dir_type(path->nodes[0], di); > out: > btrfs_free_path(path); > return ret; > @@ -5667,6 +5670,11 @@ static struct inode *new_simple_dir(struct super_block *s, > return inode; > } > > +static inline u8 btrfs_inode_type(struct inode *inode) > +{ > + return btrfs_type_by_mode[(inode->i_mode & S_IFMT) >> S_SHIFT]; > +} > + > struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry) > { > struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb); > @@ -5674,18 +5682,29 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry) > struct btrfs_root *root = BTRFS_I(dir)->root; > struct btrfs_root *sub_root = root; > struct btrfs_key location; > + u8 di_type = 0; > int index; > int ret = 0; > > if (dentry->d_name.len > BTRFS_NAME_LEN) > return ERR_PTR(-ENAMETOOLONG); > > - ret = btrfs_inode_by_name(dir, dentry, &location); > + ret = btrfs_inode_by_name(dir, dentry, &location, &di_type); > if (ret < 0) > return ERR_PTR(ret); > > if (location.type == BTRFS_INODE_ITEM_KEY) { > inode = btrfs_iget(dir->i_sb, &location, root, NULL); > + > + /* Do extra check against inode mode with di_type */ > + if (btrfs_inode_type(inode) != di_type) { > + btrfs_crit(fs_info, > +"inode mode mismatch with dir: inode mode=0%o btrfs type=%u dir type=%u", > + inode->i_mode, btrfs_inode_type(inode), > + di_type); > + iput(inode); > + return ERR_PTR(-EUCLEAN); > + } > return inode; > } > > @@ -6290,11 +6309,6 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans, > return ERR_PTR(ret); > } > > -static inline u8 btrfs_inode_type(struct inode *inode) > -{ > - return btrfs_type_by_mode[(inode->i_mode & S_IFMT) >> S_SHIFT]; > -} > - > /* > * utility function to add 'inode' into 'parent_inode' with > * a give name and a given sequence number. > @@ -6816,6 +6830,14 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode, > extent_start = found_key.offset; > if (found_type == BTRFS_FILE_EXTENT_REG || > found_type == BTRFS_FILE_EXTENT_PREALLOC) { > + /* Only regular file could have regular/prealloc extent */ > + if (!S_ISREG(inode->vfs_inode.i_mode)) { > + ret = -EUCLEAN; > + btrfs_crit(fs_info, > + "regular/prealloc extent found for non-regular inode %llu", > + btrfs_ino(inode)); > + goto out; > + } > extent_end = extent_start + > btrfs_file_extent_num_bytes(leaf, item); > > diff --git a/fs/btrfs/tests/inode-tests.c b/fs/btrfs/tests/inode-tests.c > index af0c8e30d9e2..b01dbcab9eed 100644 > --- a/fs/btrfs/tests/inode-tests.c > +++ b/fs/btrfs/tests/inode-tests.c > @@ -232,6 +232,7 @@ static noinline int test_btrfs_get_extent(u32 sectorsize, u32 nodesize) > return ret; > } > > + inode->i_mode = S_IFREG; > BTRFS_I(inode)->location.type = BTRFS_INODE_ITEM_KEY; > BTRFS_I(inode)->location.objectid = BTRFS_FIRST_FREE_OBJECTID; > BTRFS_I(inode)->location.offset = 0; >