linux-stable.git/fs/ext4, branch v4.6.4

ext4: silence UBSAN in ext4_mb_init()

2016-06-08T01:23:42+00:00

commit 935244cd54b86ca46e69bc6604d2adfb1aec2d42 upstream.

Currently, in ext4_mb_init(), there's a loop like the following:

  do {
    ...
    offset += 1 << (sb->s_blocksize_bits - i);
    i++;
  } while (i <= sb->s_blocksize_bits + 1);

Note that the updated offset is used in the loop's next iteration only.

However, at the last iteration, that is at i == sb->s_blocksize_bits + 1,
the shift count becomes equal to (unsigned)-1 > 31 (c.f. C99 6.5.7(3))
and UBSAN reports

  UBSAN: Undefined behaviour in fs/ext4/mballoc.c:2621:15
  shift exponent 4294967295 is too large for 32-bit type 'int'
  [...]
  Call Trace:
   [] dump_stack+0xbc/0x117
   [] ? _atomic_dec_and_lock+0x169/0x169
   [] ubsan_epilogue+0xd/0x4e
   [] __ubsan_handle_shift_out_of_bounds+0x1fb/0x254
   [] ? __ubsan_handle_load_invalid_value+0x158/0x158
   [] ? kmem_cache_alloc+0x101/0x390
   [] ? ext4_mb_init+0x13b/0xfd0
   [] ? create_cache+0x57/0x1f0
   [] ? create_cache+0x11a/0x1f0
   [] ? mutex_lock+0x38/0x60
   [] ? mutex_unlock+0x1b/0x50
   [] ? put_online_mems+0x5b/0xc0
   [] ? kmem_cache_create+0x117/0x2c0
   [] ext4_mb_init+0xc49/0xfd0
   [...]

Observe that the mentioned shift exponent, 4294967295, equals (unsigned)-1.

Unless compilers start to do some fancy transformations (which at least
GCC 6.0.0 doesn't currently do), the issue is of cosmetic nature only: the
such calculated value of offset is never used again.

Silence UBSAN by introducing another variable, offset_incr, holding the
next increment to apply to offset and adjust that one by right shifting it
by one position per loop iteration.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=114701
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=112161

Signed-off-by: Nicolai Stange 
Signed-off-by: Theodore Ts'o 
Signed-off-by: Greg Kroah-Hartman

ext4: address UBSAN warning in mb_find_order_for_block()

2016-06-08T01:23:42+00:00

commit b5cb316cdf3a3f5f6125412b0f6065185240cfdc upstream.

Currently, in mb_find_order_for_block(), there's a loop like the following:

  while (order <= e4b->bd_blkbits + 1) {
    ...
    bb += 1 << (e4b->bd_blkbits - order);
  }

Note that the updated bb is used in the loop's next iteration only.

However, at the last iteration, that is at order == e4b->bd_blkbits + 1,
the shift count becomes negative (c.f. C99 6.5.7(3)) and UBSAN reports

  UBSAN: Undefined behaviour in fs/ext4/mballoc.c:1281:11
  shift exponent -1 is negative
  [...]
  Call Trace:
   [] dump_stack+0xbc/0x117
   [] ? _atomic_dec_and_lock+0x169/0x169
   [] ubsan_epilogue+0xd/0x4e
   [] __ubsan_handle_shift_out_of_bounds+0x1fb/0x254
   [] ? __ubsan_handle_load_invalid_value+0x158/0x158
   [] ? ext4_mb_generate_from_pa+0x590/0x590
   [] ? ext4_read_block_bitmap_nowait+0x598/0xe80
   [] mb_find_order_for_block+0x1ce/0x240
   [...]

Unless compilers start to do some fancy transformations (which at least
GCC 6.0.0 doesn't currently do), the issue is of cosmetic nature only: the
such calculated value of bb is never used again.

Silence UBSAN by introducing another variable, bb_incr, holding the next
increment to apply to bb and adjust that one by right shifting it by one
position per loop iteration.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=114701
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=112161

Signed-off-by: Nicolai Stange 
Signed-off-by: Theodore Ts'o 
Signed-off-by: Greg Kroah-Hartman

ext4: fix oops on corrupted filesystem

2016-06-08T01:23:42+00:00

commit 74177f55b70e2f2be770dd28684dd6d17106a4ba upstream.

When filesystem is corrupted in the right way, it can happen
ext4_mark_iloc_dirty() in ext4_orphan_add() returns error and we
subsequently remove inode from the in-memory orphan list. However this
deletion is done with list_del(&EXT4_I(inode)->i_orphan) and thus we
leave i_orphan list_head with a stale content. Later we can look at this
content causing list corruption, oops, or other issues. The reported
trace looked like:

WARNING: CPU: 0 PID: 46 at lib/list_debug.c:53 __list_del_entry+0x6b/0x100()
list_del corruption, 0000000061c1d6e0->next is LIST_POISON1
0000000000100100)
CPU: 0 PID: 46 Comm: ext4.exe Not tainted 4.1.0-rc4+ #250
Stack:
 60462947 62219960 602ede24 62219960
 602ede24 603ca293 622198f0 602f02eb
 62219950 6002c12c 62219900 601b4d6b
Call Trace:
 [<6005769c>] ? vprintk_emit+0x2dc/0x5c0
 [<602ede24>] ? printk+0x0/0x94
 [<600190bc>] show_stack+0xdc/0x1a0
 [<602ede24>] ? printk+0x0/0x94
 [<602ede24>] ? printk+0x0/0x94
 [<602f02eb>] dump_stack+0x2a/0x2c
 [<6002c12c>] warn_slowpath_common+0x9c/0xf0
 [<601b4d6b>] ? __list_del_entry+0x6b/0x100
 [<6002c254>] warn_slowpath_fmt+0x94/0xa0
 [<602f4d09>] ? __mutex_lock_slowpath+0x239/0x3a0
 [<6002c1c0>] ? warn_slowpath_fmt+0x0/0xa0
 [<60023ebf>] ? set_signals+0x3f/0x50
 [<600a205a>] ? kmem_cache_free+0x10a/0x180
 [<602f4e88>] ? mutex_lock+0x18/0x30
 [<601b4d6b>] __list_del_entry+0x6b/0x100
 [<601177ec>] ext4_orphan_del+0x22c/0x2f0
 [<6012f27c>] ? __ext4_journal_start_sb+0x2c/0xa0
 [<6010b973>] ? ext4_truncate+0x383/0x390
 [<6010bc8b>] ext4_write_begin+0x30b/0x4b0
 [<6001bb50>] ? copy_from_user+0x0/0xb0
 [<601aa840>] ? iov_iter_fault_in_readable+0xa0/0xc0
 [<60072c4f>] generic_perform_write+0xaf/0x1e0
 [<600c4166>] ? file_update_time+0x46/0x110
 [<60072f0f>] __generic_file_write_iter+0x18f/0x1b0
 [<6010030f>] ext4_file_write_iter+0x15f/0x470
 [<60094e10>] ? unlink_file_vma+0x0/0x70
 [<6009b180>] ? unlink_anon_vmas+0x0/0x260
 [<6008f169>] ? free_pgtables+0xb9/0x100
 [<600a6030>] __vfs_write+0xb0/0x130
 [<600a61d5>] vfs_write+0xa5/0x170
 [<600a63d6>] SyS_write+0x56/0xe0
 [<6029fcb0>] ? __libc_waitpid+0x0/0xa0
 [<6001b698>] handle_syscall+0x68/0x90
 [<6002633d>] userspace+0x4fd/0x600
 [<6002274f>] ? save_registers+0x1f/0x40
 [<60028bd7>] ? arch_prctl+0x177/0x1b0
 [<60017bd5>] fork_handler+0x85/0x90

Fix the problem by using list_del_init() as we always should with
i_orphan list.

Reported-by: Vegard Nossum 
Signed-off-by: Jan Kara 
Signed-off-by: Theodore Ts'o 
Signed-off-by: Greg Kroah-Hartman

ext4: fix check of dqget() return value in ext4_ioctl_setproject()

2016-06-08T01:23:42+00:00

commit ff0bc08454917964291f72ee5b8eca66de4bc250 upstream.

A failed call to dqget() returns an ERR_PTR() and not null. Fix
the check in ext4_ioctl_setproject() to handle this correctly.

Fixes: 9b7365fc1c82 ("ext4: add FS_IOC_FSSETXATTR/FS_IOC_FSGETXATTR interface support")
Signed-off-by: Seth Forshee 
Signed-off-by: Theodore Ts'o 
Reviewed-by: Jan Kara 
Signed-off-by: Greg Kroah-Hartman

ext4: clean up error handling when orphan list is corrupted

2016-06-08T01:23:42+00:00

commit 7827a7f6ebfcb7f388dc47fddd48567a314701ba upstream.

Instead of just printing warning messages, if the orphan list is
corrupted, declare the file system is corrupted.  If there are any
reserved inodes in the orphaned inode list, declare the file system
corrupted and stop right away to avoid doing more potential damage to
the file system.

Signed-off-by: Theodore Ts'o 
Signed-off-by: Greg Kroah-Hartman

ext4: fix hang when processing corrupted orphaned inode list

2016-06-08T01:23:42+00:00

commit c9eb13a9105e2e418f72e46a2b6da3f49e696902 upstream.

If the orphaned inode list contains inode #5, ext4_iget() returns a
bad inode (since the bootloader inode should never be referenced
directly).  Because of the bad inode, we end up processing the inode
repeatedly and this hangs the machine.

This can be reproduced via:

   mke2fs -t ext4 /tmp/foo.img 100
   debugfs -w -R "ssv last_orphan 5" /tmp/foo.img
   mount -o loop /tmp/foo.img /mnt

(But don't do this if you are using an unpatched kernel if you care
about the system staying functional.  :-)

This bug was found by the port of American Fuzzy Lop into the kernel
to find file system problems[1].  (Since it *only* happens if inode #5
shows up on the orphan list --- 3, 7, 8, etc. won't do it, it's not
surprising that AFL needed two hours before it found it.)

[1] http://events.linuxfoundation.org/sites/events/files/slides/AFL%20filesystem%20fuzzing%2C%20Vault%202016_0.pdf

Reported by: Vegard Nossum 
Signed-off-by: Theodore Ts'o 
Signed-off-by: Greg Kroah-Hartman

ext4: fix data exposure after a crash

2016-06-08T01:23:41+00:00

commit 06bd3c36a733ac27962fea7d6f47168841376824 upstream.

Huang has reported that in his powerfail testing he is seeing stale
block contents in some of recently allocated blocks although he mounts
ext4 in data=ordered mode. After some investigation I have found out
that indeed when delayed allocation is used, we don't add inode to
transaction's list of inodes needing flushing before commit. Originally
we were doing that but commit f3b59291a69d removed the logic with a
flawed argument that it is not needed.

The problem is that although for delayed allocated blocks we write their
contents immediately after allocating them, there is no guarantee that
the IO scheduler or device doesn't reorder things and thus transaction
allocating blocks and attaching them to inode can reach stable storage
before actual block contents. Actually whenever we attach freshly
allocated blocks to inode using a written extent, we should add inode to
transaction's ordered inode list to make sure we properly wait for block
contents to be written before committing the transaction. So that is
what we do in this patch. This also handles other cases where stale data
exposure was possible - like filling hole via mmap in
data=ordered,nodelalloc mode.

The only exception to the above rule are extending direct IO writes where
blkdev_direct_IO() waits for IO to complete before increasing i_size and
thus stale data exposure is not possible. For now we don't complicate
the code with optimizing this special case since the overhead is pretty
low. In case this is observed to be a performance problem we can always
handle it using a special flag to ext4_map_blocks().

Fixes: f3b59291a69d0b734be1fc8be489fef2dd846d3d
Reported-by: "HUANG Weller (CM/ESW12-CN)" 
Tested-by: "HUANG Weller (CM/ESW12-CN)" 
Signed-off-by: Jan Kara 
Signed-off-by: Theodore Ts'o 
Signed-off-by: Greg Kroah-Hartman

ext4/fscrypto: avoid RCU lookup in d_revalidate

2016-04-13T03:01:35+00:00

As Al pointed, d_revalidate should return RCU lookup before using d_inode.
This was originally introduced by:
commit 34286d666230 ("fs: rcu-walk aware d_revalidate method").

Reported-by: Al Viro 
Signed-off-by: Jaegeuk Kim 
Cc: Theodore Ts'o 
Cc: stable

Revert "ext4: allow readdir()'s of large empty directories to be interrupted"

2016-04-10T23:52:24+00:00

This reverts commit 1028b55bafb7611dda1d8fed2aeca16a436b7dff.

It's broken: it makes ext4 return an error at an invalid point, causing
the readdir wrappers to write the the position of the last successful
directory entry into the position field, which means that the next
readdir will now return that last successful entry _again_.

You can only return fatal errors (that terminate the readdir directory
walk) from within the filesystem readdir functions, the "normal" errors
(that happen when the readdir buffer fills up, for example) happen in
the iterorator where we know the position of the actual failing entry.

I do have a very different patch that does the "signal_pending()"
handling inside the iterator function where it is allowable, but while
that one passes all the sanity checks, I screwed up something like four
times while emailing it out, so I'm not going to commit it today.

So my track record is not good enough, and the stars will have to align
better before that one gets committed.  And it would be good to get some
review too, of course, since celestial alignments are always an iffy
debugging model.

IOW, let's just revert the commit that caused the problem for now.

Reported-by: Greg Thelen 
Cc: Theodore Ts'o 
Signed-off-by: Linus Torvalds

Merge tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2016-04-08T00:22:20+00:00

Pull ext4 bugfixes from Ted Ts'o:
 "These changes contains a fix for overlayfs interacting with some
  (badly behaved) dentry code in various file systems.  These have been
  reviewed by Al and the respective file system mtinainers and are going
  through the ext4 tree for convenience.

  This also has a few ext4 encryption bug fixes that were discovered in
  Android testing (yes, we will need to get these sync'ed up with the
  fs/crypto code; I'll take care of that).  It also has some bug fixes
  and a change to ignore the legacy quota options to allow for xfstests
  regression testing of ext4's internal quota feature and to be more
  consistent with how xfs handles this case"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: ignore quota mount options if the quota feature is enabled
  ext4 crypto: fix some error handling
  ext4: avoid calling dquot_get_next_id() if quota is not enabled
  ext4: retry block allocation for failed DIO and DAX writes
  ext4: add lockdep annotations for i_data_sem
  ext4: allow readdir()'s of large empty directories to be interrupted
  btrfs: fix crash/invalid memory access on fsync when using overlayfs
  ext4 crypto: use dget_parent() in ext4_d_revalidate()
  ext4: use file_dentry()
  ext4: use dget_parent() in ext4_file_open()
  nfs: use file_dentry()
  fs: add file_dentry()
  ext4 crypto: don't let data integrity writebacks fail with ENOMEM
  ext4: check if in-inode xattr is corrupted in ext4_expand_extra_isize_ea()