Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934239AbbHJKRs (ORCPT ); Mon, 10 Aug 2015 06:17:48 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:44185 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934110AbbHJKRk (ORCPT ); Mon, 10 Aug 2015 06:17:40 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Filipe Manana" Date: Mon, 10 Aug 2015 12:12:31 +0200 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 081/110] Btrfs: fix file corruption after cloning inline extents In-Reply-To: X-SA-Exim-Connect-IP: 2.173.94.72 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6525 Lines: 132 3.2.71-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Filipe Manana commit ed958762644b404654a6f5d23e869f496fe127c6 upstream. Using the clone ioctl (or extent_same ioctl, which calls the same extent cloning function as well) we end up allowing copy an inline extent from the source file into a non-zero offset of the destination file. This is something not expected and that the btrfs code is not prepared to deal with - all inline extents must be at a file offset equals to 0. For example, the following excerpt of a test case for fstests triggers a crash/BUG_ON() on a write operation after an inline extent is cloned into a non-zero offset: _scratch_mkfs >>$seqres.full 2>&1 _scratch_mount # Create our test files. File foo has the same 2K of data at offset 4K # as file bar has at its offset 0. $XFS_IO_PROG -f -s -c "pwrite -S 0xaa 0 4K" \ -c "pwrite -S 0xbb 4k 2K" \ -c "pwrite -S 0xcc 8K 4K" \ $SCRATCH_MNT/foo | _filter_xfs_io # File bar consists of a single inline extent (2K size). $XFS_IO_PROG -f -s -c "pwrite -S 0xbb 0 2K" \ $SCRATCH_MNT/bar | _filter_xfs_io # Now call the clone ioctl to clone the extent of file bar into file # foo at its offset 4K. This made file foo have an inline extent at # offset 4K, something which the btrfs code can not deal with in future # IO operations because all inline extents are supposed to start at an # offset of 0, resulting in all sorts of chaos. # So here we validate that clone ioctl returns an EOPNOTSUPP, which is # what it returns for other cases dealing with inlined extents. $CLONER_PROG -s 0 -d $((4 * 1024)) -l $((2 * 1024)) \ $SCRATCH_MNT/bar $SCRATCH_MNT/foo # Because of the inline extent at offset 4K, the following write made # the kernel crash with a BUG_ON(). $XFS_IO_PROG -c "pwrite -S 0xdd 6K 2K" $SCRATCH_MNT/foo | _filter_xfs_io status=0 exit The stack trace of the BUG_ON() triggered by the last write is: [152154.035903] ------------[ cut here ]------------ [152154.036424] kernel BUG at mm/page-writeback.c:2286! [152154.036424] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [152154.036424] Modules linked in: btrfs dm_flakey dm_mod crc32c_generic xor raid6_pq nfsd auth_rpcgss oid_registry nfs_acl nfs lockd grace fscache sunrpc loop fuse parport_pc acpi_cpu$ [152154.036424] CPU: 2 PID: 17873 Comm: xfs_io Tainted: G W 4.1.0-rc6-btrfs-next-11+ #2 [152154.036424] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.1-0-g4adadbd-20150316_085822-nilsson.home.kraxel.org 04/01/2014 [152154.036424] task: ffff880429f70990 ti: ffff880429efc000 task.ti: ffff880429efc000 [152154.036424] RIP: 0010:[] [] clear_page_dirty_for_io+0x1e/0x90 [152154.036424] RSP: 0018:ffff880429effc68 EFLAGS: 00010246 [152154.036424] RAX: 0200000000000806 RBX: ffffea0006a6d8f0 RCX: 0000000000000001 [152154.036424] RDX: 0000000000000000 RSI: ffffffff81155d1b RDI: ffffea0006a6d8f0 [152154.036424] RBP: ffff880429effc78 R08: ffff8801ce389fe0 R09: 0000000000000001 [152154.036424] R10: 0000000000002000 R11: ffffffffffffffff R12: ffff8800200dce68 [152154.036424] R13: 0000000000000000 R14: ffff8800200dcc88 R15: ffff8803d5736d80 [152154.036424] FS: 00007fbf119f6700(0000) GS:ffff88043d280000(0000) knlGS:0000000000000000 [152154.036424] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [152154.036424] CR2: 0000000001bdc000 CR3: 00000003aa555000 CR4: 00000000000006e0 [152154.036424] Stack: [152154.036424] ffff8803d5736d80 0000000000000001 ffff880429effcd8 ffffffffa04e97c1 [152154.036424] ffff880429effd68 ffff880429effd60 0000000000000001 ffff8800200dc9c8 [152154.036424] 0000000000000001 ffff8800200dcc88 0000000000000000 0000000000001000 [152154.036424] Call Trace: [152154.036424] [] lock_and_cleanup_extent_if_need+0x147/0x18d [btrfs] [152154.036424] [] __btrfs_buffered_write+0x245/0x4c8 [btrfs] [152154.036424] [] ? btrfs_file_write_iter+0x150/0x3e0 [btrfs] [152154.036424] [] ? btrfs_file_write_iter+0x15f/0x3e0 [btrfs] [152154.036424] [] btrfs_file_write_iter+0x2cc/0x3e0 [btrfs] [152154.036424] [] __vfs_write+0x7c/0xa5 [152154.036424] [] vfs_write+0xa0/0xe4 [152154.036424] [] SyS_pwrite64+0x64/0x82 [152154.036424] [] system_call_fastpath+0x12/0x6f [152154.036424] Code: 48 89 c7 e8 0f ff ff ff 5b 41 5c 5d c3 0f 1f 44 00 00 55 48 89 e5 41 54 53 48 89 fb e8 ae ef 00 00 49 89 c4 48 8b 03 a8 01 75 02 <0f> 0b 4d 85 e4 74 59 49 8b 3c 2$ [152154.036424] RIP [] clear_page_dirty_for_io+0x1e/0x90 [152154.036424] RSP [152154.242621] ---[ end trace e3d3376b23a57041 ]--- Fix this by returning the error EOPNOTSUPP if an attempt to copy an inline extent into a non-zero offset happens, just like what is done for other scenarios that would require copying/splitting inline extents, which were introduced by the following commits: 00fdf13a2e9f ("Btrfs: fix a crash of clone with inline extents's split") 3f9e3df8da3c ("btrfs: replace error code from btrfs_drop_extents") Signed-off-by: Filipe Manana [bwh: Backported to 3.2: test new_key.offset as last_dest_end isn't defined in this function] Signed-off-by: Ben Hutchings --- fs/btrfs/ioctl.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2448,6 +2448,20 @@ static noinline long btrfs_ioctl_clone(s new_key.offset += skip; } + /* + * Don't copy an inline extent into an offset + * greater than zero. Having an inline extent + * at such an offset results in chaos as btrfs + * isn't prepared for such cases. Just skip + * this case for the same reasons as commented + * at btrfs_ioctl_clone(). + */ + if (new_key.offset > 0) { + ret = -EOPNOTSUPP; + btrfs_end_transaction(trans, root); + goto out; + } + if (key.offset + datal > off+len) trim = key.offset + datal - (off+len); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/