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  1. 06 Jan, 2022 1 commit
  3. 22 Dec, 2021 1 commit
    • Darrick J. Wong's avatar
      xfs: prevent UAF in xfs_log_item_in_current_chkpt · f8d92a66
      Darrick J. Wong authored 
      While I was running with KASAN and lockdep enabled, I stumbled upon an
KASAN report about a UAF to a freed CIL checkpoint.  Looking at the
comment for xfs_log_item_in_current_chkpt, it seems pretty obvious to me
that the original patch to xfs_defer_finish_noroll should have done
something to lock the CIL to prevent it from switching the CIL contexts
while the predicate runs.

For upper level code that needs to know if a given log item is new
enough not to need relogging, add a new wrapper that takes the CIL
context lock long enough to sample the current CIL context.  This is
kind of racy in that the CIL can switch the contexts immediately after
sampling, but that's ok because the consequence is that the defer ops
code is a little slow to relog items.

 ==================================================================
 BUG: KASAN: use-after-free in xfs_log_item_in_current_chkpt+0x139/0x160 [xfs]
 Read of size 8 at addr ffff88804ea5f608 by task fsstress/527999

 CPU: 1 PID: 527999 Comm: fsstress Tainted: G      D      5.16.0-rc4-xfsx #rc4
 Call Trace:
  <TASK>
  dump_stack_lvl+0x45/0x59
  print_address_description.constprop.0+0x1f/0x140
  kasan_report.cold+0x83/0xdf
  xfs_log_item_in_current_chkpt+0x139/0x160
  xfs_defer_finish_noroll+0x3bb/0x1e30
  __xfs_trans_commit+0x6c8/0xcf0
  xfs_reflink_remap_extent+0x66f/0x10e0
  xfs_reflink_remap_blocks+0x2dd/0xa90
  xfs_file_remap_range+0x27b/0xc30
  vfs_dedupe_file_range_one+0x368/0x420
  vfs_dedupe_file_range+0x37c/0x5d0
  do_vfs_ioctl+0x308/0x1260
  __x64_sys_ioctl+0xa1/0x170
  do_syscall_64+0x35/0x80
  entry_SYSCALL_64_after_hwframe+0x44/0xae
 RIP: 0033:0x7f2c71a2950b
 Code: 0f 1e fa 48 8b 05 85 39 0d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff
ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01
f0 ff ff 73 01 c3 48 8b 0d 55 39 0d 00 f7 d8 64 89 01 48
 RSP: 002b:00007ffe8c0e03c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
 RAX: ffffffffffffffda RBX: 00005600862a8740 RCX: 00007f2c71a2950b
 RDX: 00005600862a7be0 RSI: 00000000c0189436 RDI: 0000000000000004
 RBP: 000000000000000b R08: 0000000000000027 R09: 0000000000000003
 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000005a
 R13: 00005600862804a8 R14: 0000000000016000 R15: 00005600862a8a20
  </TASK>

 Allocated by task 464064:
  kasan_save_stack+0x1e/0x50
  __kasan_kmalloc+0x81/0xa0
  kmem_alloc+0xcd/0x2c0 [xfs]
  xlog_cil_ctx_alloc+0x17/0x1e0 [xfs]
  xlog_cil_push_work+0x141/0x13d0 [xfs]
  process_one_work+0x7f6/0x1380
  worker_thread+0x59d/0x1040
  kthread+0x3b0/0x490
  ret_from_fork+0x1f/0x30

 Freed by task 51:
  kasan_save_stack+0x1e/0x50
  kasan_set_track+0x21/0x30
  kasan_set_free_info+0x20/0x30
  __kasan_slab_free+0xed/0x130
  slab_free_freelist_hook+0x7f/0x160
  kfree+0xde/0x340
  xlog_cil_committed+0xbfd/0xfe0 [xfs]
  xlog_cil_process_committed+0x103/0x1c0 [xfs]
  xlog_state_do_callback+0x45d/0xbd0 [xfs]
  xlog_ioend_work+0x116/0x1c0 [xfs]
  process_one_work+0x7f6/0x1380
  worker_thread+0x59d/0x1040
  kthread+0x3b0/0x490
  ret_from_fork+0x1f/0x30

 Last potentially related work creation:
  kasan_save_stack+0x1e/0x50
  __kasan_record_aux_stack+0xb7/0xc0
  insert_work+0x48/0x2e0
  __queue_work+0x4e7/0xda0
  queue_work_on+0x69/0x80
  xlog_cil_push_now.isra.0+0x16b/0x210 [xfs]
  xlog_cil_force_seq+0x1b7/0x850 [xfs]
  xfs_log_force_seq+0x1c7/0x670 [xfs]
  xfs_file_fsync+0x7c1/0xa60 [xfs]
  __x64_sys_fsync+0x52/0x80
  do_syscall_64+0x35/0x80
  entry_SYSCALL_64_after_hwframe+0x44/0xae

 The buggy address belongs to the object at ffff88804ea5f600
  which belongs to the cache kmalloc-256 of size 256
 The buggy address is located 8 bytes inside of
  256-byte region [ffff88804ea5f600, ffff88804ea5f700)
 The buggy address belongs to the page:
 page:ffffea00013a9780 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88804ea5ea00 pfn:0x4ea5e
 head:ffffea00013a9780 order:1 compound_mapcount:0
 flags: 0x4fff80000010200(slab|head|node=1|zone=1|lastcpupid=0xfff)
 raw: 04fff80000010200 ffffea0001245908 ffffea00011bd388 ffff888004c42b40
 raw: ffff88804ea5ea00 0000000000100009 00000001ffffffff 0000000000000000
 page dumped because: kasan: bad access detected

 Memory state around the buggy address:
  ffff88804ea5f500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff88804ea5f580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 >ffff88804ea5f600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                       ^
  ffff88804ea5f680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff88804ea5f700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ==================================================================

Fixes: 4e919af7 ("xfs: periodically relog deferred intent items")
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
      f8d92a66
  5. 21 Dec, 2021 8 commits
    • Dan Carpenter's avatar
      xfs: prevent a WARN_ONCE() in xfs_ioc_attr_list() · 6ed6356b
      Dan Carpenter authored 
      The "bufsize" comes from the root user.  If "bufsize" is negative then,
because of type promotion, neither of the validation checks at the start
of the function are able to catch it:

	if (bufsize < sizeof(struct xfs_attrlist) ||
	    bufsize > XFS_XATTR_LIST_MAX)
		return -EINVAL;

This means "bufsize" will trigger (WARN_ON_ONCE(size > INT_MAX)) in
kvmalloc_node().  Fix this by changing the type from int to size_t.
Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
      6ed6356b
    • Yang Xu's avatar
      xfs: Fix comments mentioning xfs_ialloc · 132c460e
      Yang Xu authored 
      Since kernel commit 1abcf261 ("xfs: move on-disk inode allocation out of xfs_ialloc()"),
xfs_ialloc has been renamed to xfs_init_new_inode. So update this in comments.
Signed-off-by: default avatarYang Xu <xuyang2018.jy@fujitsu.com>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
      132c460e
    • Dave Chinner's avatar
      xfs: check sb_meta_uuid for dabuf buffer recovery · 09654ed8
      Dave Chinner authored 
      Got a report that a repeated crash test of a container host would
eventually fail with a log recovery error preventing the system from
mounting the root filesystem. It manifested as a directory leaf node
corruption on writeback like so:

 XFS (loop0): Mounting V5 Filesystem
 XFS (loop0): Starting recovery (logdev: internal)
 XFS (loop0): Metadata corruption detected at xfs_dir3_leaf_check_int+0x99/0xf0, xfs_dir3_leaf1 block 0x12faa158
 XFS (loop0): Unmount and run xfs_repair
 XFS (loop0): First 128 bytes of corrupted metadata buffer:
 00000000: 00 00 00 00 00 00 00 00 3d f1 00 00 e1 9e d5 8b  ........=.......
 00000010: 00 00 00 00 12 fa a1 58 00 00 00 29 00 00 1b cc  .......X...)....
 00000020: 91 06 78 ff f7 7e 4a 7d 8d 53 86 f2 ac 47 a8 23  ..x..~J}.S...G.#
 00000030: 00 00 00 00 17 e0 00 80 00 43 00 00 00 00 00 00  .........C......
 00000040: 00 00 00 2e 00 00 00 08 00 00 17 2e 00 00 00 0a  ................
 00000050: 02 35 79 83 00 00 00 30 04 d3 b4 80 00 00 01 50  .5y....0.......P
 00000060: 08 40 95 7f 00 00 02 98 08 41 fe b7 00 00 02 d4  .@.......A......
 00000070: 0d 62 ef a7 00 00 01 f2 14 50 21 41 00 00 00 0c  .b.......P!A....
 XFS (loop0): Corruption of in-memory data (0x8) detected at xfs_do_force_shutdown+0x1a/0x20 (fs/xfs/xfs_buf.c:1514).  Shutting down.
 XFS (loop0): Please unmount the filesystem and rectify the problem(s)
 XFS (loop0): log mount/recovery failed: error -117
 XFS (loop0): log mount failed

Tracing indicated that we were recovering changes from a transaction
at LSN 0x29/0x1c16 into a buffer that had an LSN of 0x29/0x1d57.
That is, log recovery was overwriting a buffer with newer changes on
disk than was in the transaction. Tracing indicated that we were
hitting the "recovery immediately" case in
xfs_buf_log_recovery_lsn(), and hence it was ignoring the LSN in the
buffer.

The code was extracting the LSN correctly, then ignoring it because
the UUID in the buffer did not match the superblock UUID. The
problem arises because the UUID check uses the wrong UUID - it
should be checking the sb_meta_uuid, not sb_uuid. This filesystem
has sb_uuid != sb_meta_uuid (which is fine), and the buffer has the
correct matching sb_meta_uuid in it, it's just the code checked it
against the wrong superblock uuid.

The is no corruption in the filesystem, and failing to recover the
buffer due to a write verifier failure means the recovery bug did
not propagate the corruption to disk. Hence there is no corruption
before or after this bug has manifested, the impact is limited
simply to an unmountable filesystem....

This was missed back in 2015 during an audit of incorrect sb_uuid
usage that resulted in commit fcfbe2c4 ("xfs: log recovery needs
to validate against sb_meta_uuid") that fixed the magic32 buffers to
validate against sb_meta_uuid instead of sb_uuid. It missed the
magicda buffers....

Fixes: ce748eaa ("xfs: create new metadata UUID field and incompat flag")
Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
      09654ed8
    • Darrick J. Wong's avatar
      xfs: fix a bug in the online fsck directory leaf1 bestcount check · e5d1802c
      Darrick J. Wong authored 
      When xfs_scrub encounters a directory with a leaf1 block, it tries to
validate that the leaf1 block's bestcount (aka the best free count of
each directory data block) is the correct size.  Previously, this author
believed that comparing bestcount to the directory isize (since
directory data blocks are under isize, and leaf/bestfree blocks are
above it) was sufficient.

Unfortunately during testing of online repair, it was discovered that it
is possible to create a directory with a hole between the last directory
block and isize.  The directory code seems to handle this situation just
fine and xfs_repair doesn't complain, which effectively makes this quirk
part of the disk format.

Fix the check to work properly.
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
      e5d1802c
    • Darrick J. Wong's avatar
      xfs: only run COW extent recovery when there are no live extents · 7993f1a4
      Darrick J. Wong authored 
      As part of multiple customer escalations due to file data corruption
after copy on write operations, I wrote some fstests that use fsstress
to hammer on COW to shake things loose.  Regrettably, I caught some
filesystem shutdowns due to incorrect rmap operations with the following
loop:

mount <filesystem>				# (0)
fsstress <run only readonly ops> &		# (1)
while true; do
	fsstress <run all ops>
	mount -o remount,ro			# (2)
	fsstress <run only readonly ops>
	mount -o remount,rw			# (3)
done

When (2) happens, notice that (1) is still running.  xfs_remount_ro will
call xfs_blockgc_stop to walk the inode cache to free all the COW
extents, but the blockgc mechanism races with (1)'s reader threads to
take IOLOCKs and loses, which means that it doesn't clean them all out.
Call such a file (A).

When (3) happens, xfs_remount_rw calls xfs_reflink_recover_cow, which
walks the ondisk refcount btree and frees any COW extent that it finds.
This function does not check the inode cache, which means that incore
COW forks of inode (A) is now inconsistent with the ondisk metadata.  If
one of those former COW extents are allocated and mapped into another
file (B) and someone triggers a COW to the stale reservation in (A), A's
dirty data will be written into (B) and once that's done, those blocks
will be transferred to (A)'s data fork without bumping the refcount.

The results are catastrophic -- file (B) and the refcount btree are now
corrupt.  In the first patch, we fixed the race condition in (2) so that
(A) will always flush the COW fork.  In this second patch, we move the
_recover_cow call to the initial mount call in (0) for safety.

As mentioned previously, xfs_reflink_recover_cow walks the refcount
btree looking for COW staging extents, and frees them.  This was
intended to be run at mount time (when we know there are no live inodes)
to clean up any leftover staging events that may have been left behind
during an unclean shutdown.  As a time "optimization" for readonly
mounts, we deferred this to the ro->rw transition, not realizing that
any failure to clean all COW forks during a rw->ro transition would
result in catastrophic corruption.

Therefore, remove this optimization and only run the recovery routine
when we're guaranteed not to have any COW staging extents anywhere,
which means we always run this at mount time.  While we're at it, move
the callsite to xfs_log_mount_finish because any refcount btree
expansion (however unlikely given that we're removing records from the
right side of the index) must be fed by a per-AG reservation, which
doesn't exist in its current location.

Fixes: 174edb0e ("xfs: store in-progress CoW allocations in the refcount btree")
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarChandan Babu R <chandan.babu@oracle.com>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
      7993f1a4
    • Darrick J. Wong's avatar
      xfs: don't expose internal symlink metadata buffers to the vfs · 7b7820b8
      Darrick J. Wong authored 
      Ian Kent reported that for inline symlinks, it's possible for
vfs_readlink to hang on to the target buffer returned by
_vn_get_link_inline long after it's been freed by xfs inode reclaim.
This is a layering violation -- we should never expose XFS internals to
the VFS.

When the symlink has a remote target, we allocate a separate buffer,
copy the internal information, and let the VFS manage the new buffer's
lifetime.  Let's adapt the inline code paths to do this too.  It's
less efficient, but fixes the layering violation and avoids the need to
adapt the if_data lifetime to rcu rules.  Clearly I don't care about
readlink benchmarks.

As a side note, this fixes the minor locking violation where we can
access the inode data fork without taking any locks; proper locking (and
eliminating the possibility of having to switch inode_operations on a
live inode) is essential to online repair coordinating repairs
correctly.
Reported-by: default avatarIan Kent <raven@themaw.net>
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
      7b7820b8
    • Darrick J. Wong's avatar
      xfs: fix quotaoff mutex usage now that we don't support disabling it · 59d7fab2
      Darrick J. Wong authored 
      Prior to commit 40b52225 ("xfs: remove support for disabling quota
accounting on a mounted file system"), we used the quotaoff mutex to
protect dquot operations against quotaoff trying to pull down dquots as
part of disabling quota.

Now that we only support turning off quota enforcement, the quotaoff
mutex only protects changes in m_qflags/sb_qflags.  We don't need it to
protect dquots, which means we can remove it from setqlimits and the
dquot scrub code.  While we're at it, fix the function that forces
quotacheck, since it should have been taking the quotaoff mutex.
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
      59d7fab2
    • Darrick J. Wong's avatar
      xfs: shut down filesystem if we xfs_trans_cancel with deferred work items · 47a6df7c
      Darrick J. Wong authored 
      While debugging some very strange rmap corruption reports in connection
with the online directory repair code.  I root-caused the error to the
following incorrect sequence:

<start repair transaction>
<expand directory, causing a deferred rmap to be queued>
<roll transaction>
<cancel transaction>

Obviously, we should have committed the transaction instead of
cancelling it.  Thinking more broadly, however, xfs_trans_cancel should
have warned us that we were throwing away work item that we already
committed to performing.  This is not correct, and we need to shut down
the filesystem.

Change xfs_trans_cancel to complain in the loudest manner if we're
cancelling any transaction with deferred work items attached.
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
      47a6df7c
  7. 12 Dec, 2021 14 commits
  9. 11 Dec, 2021 16 commits
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