linux-stable.git/fs, branch v5.4.145

Revert "btrfs: compression: don't try to compress if we don't have enough pages"

2021-09-12T06:56:41+00:00

commit 4e9655763b82a91e4c341835bb504a2b1590f984 upstream.

This reverts commit f2165627319ffd33a6217275e5690b1ab5c45763.

[BUG]
It's no longer possible to create compressed inline extent after commit
f2165627319f ("btrfs: compression: don't try to compress if we don't
have enough pages").

[CAUSE]
For compression code, there are several possible reasons we have a range
that needs to be compressed while it's no more than one page.

- Compressed inline write
  The data is always smaller than one sector and the test lacks the
  condition to properly recognize a non-inline extent.

- Compressed subpage write
  For the incoming subpage compressed write support, we require page
  alignment of the delalloc range.
  And for 64K page size, we can compress just one page into smaller
  sectors.

For those reasons, the requirement for the data to be more than one page
is not correct, and is already causing regression for compressed inline
data writeback.  The idea of skipping one page to avoid wasting CPU time
could be revisited in the future.

[FIX]
Fix it by reverting the offending commit.

Reported-by: Zygo Blaxell 
Link: https://lore.kernel.org/linux-btrfs/afa2742.c084f5d6.17b6b08dffc@tnonline.net
Fixes: f2165627319f ("btrfs: compression: don't try to compress if we don't have enough pages")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Qu Wenruo 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba 
Signed-off-by: Greg Kroah-Hartman

ubifs: report correct st_size for encrypted symlinks

2021-09-12T06:56:39+00:00

commit 064c734986011390b4d111f1a99372b7f26c3850 upstream.

The stat() family of syscalls report the wrong size for encrypted
symlinks, which has caused breakage in several userspace programs.

Fix this by calling fscrypt_symlink_getattr() after ubifs_getattr() for
encrypted symlinks.  This function computes the correct size by reading
and decrypting the symlink target (if it's not already cached).

For more details, see the commit which added fscrypt_symlink_getattr().

Fixes: ca7f85be8d6c ("ubifs: Add support for encrypted symlinks")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210702065350.209646-5-ebiggers@kernel.org
Signed-off-by: Eric Biggers 
Signed-off-by: Greg Kroah-Hartman

f2fs: report correct st_size for encrypted symlinks

2021-09-12T06:56:39+00:00

commit 461b43a8f92e68e96c4424b31e15f2b35f1bbfa9 upstream.

The stat() family of syscalls report the wrong size for encrypted
symlinks, which has caused breakage in several userspace programs.

Fix this by calling fscrypt_symlink_getattr() after f2fs_getattr() for
encrypted symlinks.  This function computes the correct size by reading
and decrypting the symlink target (if it's not already cached).

For more details, see the commit which added fscrypt_symlink_getattr().

Fixes: cbaf042a3cc6 ("f2fs crypto: add symlink encryption")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210702065350.209646-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers 
Signed-off-by: Greg Kroah-Hartman

ext4: report correct st_size for encrypted symlinks

2021-09-12T06:56:38+00:00

commit 8c4bca10ceafc43b1ca0a9fab5fa27e13cbce99e upstream.

The stat() family of syscalls report the wrong size for encrypted
symlinks, which has caused breakage in several userspace programs.

Fix this by calling fscrypt_symlink_getattr() after ext4_getattr() for
encrypted symlinks.  This function computes the correct size by reading
and decrypting the symlink target (if it's not already cached).

For more details, see the commit which added fscrypt_symlink_getattr().

Fixes: f348c252320b ("ext4 crypto: add symlink encryption")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210702065350.209646-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers 
Signed-off-by: Greg Kroah-Hartman

fscrypt: add fscrypt_symlink_getattr() for computing st_size

2021-09-12T06:56:38+00:00

commit d18760560593e5af921f51a8c9b64b6109d634c2 upstream.

Add a helper function fscrypt_symlink_getattr() which will be called
from the various filesystems' ->getattr() methods to read and decrypt
the target of encrypted symlinks in order to report the correct st_size.

Detailed explanation:

As required by POSIX and as documented in various man pages, st_size for
a symlink is supposed to be the length of the symlink target.
Unfortunately, st_size has always been wrong for encrypted symlinks
because st_size is populated from i_size from disk, which intentionally
contains the length of the encrypted symlink target.  That's slightly
greater than the length of the decrypted symlink target (which is the
symlink target that userspace usually sees), and usually won't match the
length of the no-key encoded symlink target either.

This hadn't been fixed yet because reporting the correct st_size would
require reading the symlink target from disk and decrypting or encoding
it, which historically has been considered too heavyweight to do in
->getattr().  Also historically, the wrong st_size had only broken a
test (LTP lstat03) and there were no known complaints from real users.
(This is probably because the st_size of symlinks isn't used too often,
and when it is, typically it's for a hint for what buffer size to pass
to readlink() -- which a slightly-too-large size still works for.)

However, a couple things have changed now.  First, there have recently
been complaints about the current behavior from real users:

- Breakage in rpmbuild:
  https://github.com/rpm-software-management/rpm/issues/1682
  https://github.com/google/fscrypt/issues/305

- Breakage in toybox cpio:
  https://www.mail-archive.com/toybox@lists.landley.net/msg07193.html

- Breakage in libgit2: https://issuetracker.google.com/issues/189629152
  (on Android public issue tracker, requires login)

Second, we now cache decrypted symlink targets in ->i_link.  Therefore,
taking the performance hit of reading and decrypting the symlink target
in ->getattr() wouldn't be as big a deal as it used to be, since usually
it will just save having to do the same thing later.

Also note that eCryptfs ended up having to read and decrypt symlink
targets in ->getattr() as well, to fix this same issue; see
commit 3a60a1686f0d ("eCryptfs: Decrypt symlink target for stat size").

So, let's just bite the bullet, and read and decrypt the symlink target
in ->getattr() in order to report the correct st_size.  Add a function
fscrypt_symlink_getattr() which the filesystems will call to do this.

(Alternatively, we could store the decrypted size of symlinks on-disk.
But there isn't a great place to do so, and encryption is meant to hide
the original size to some extent; that property would be lost.)

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210702065350.209646-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers 
Signed-off-by: Greg Kroah-Hartman

ext4: fix race writing to an inline_data file while its xattrs are changing

2021-09-12T06:56:38+00:00

commit a54c4613dac1500b40e4ab55199f7c51f028e848 upstream.

The location of the system.data extended attribute can change whenever
xattr_sem is not taken.  So we need to recalculate the i_inline_off
field since it mgiht have changed between ext4_write_begin() and
ext4_write_end().

This means that caching i_inline_off is probably not helpful, so in
the long run we should probably get rid of it and shrink the in-memory
ext4 inode slightly, but let's fix the race the simple way for now.

Cc: stable@kernel.org
Fixes: f19d5870cbf72 ("ext4: add normal write support for inline data")
Reported-by: syzbot+13146364637c7363a7de@syzkaller.appspotmail.com
Signed-off-by: Theodore Ts'o 
Signed-off-by: Greg Kroah-Hartman

btrfs: fix NULL pointer dereference when deleting device by invalid id

2021-09-03T08:08:16+00:00

commit e4571b8c5e9ffa1e85c0c671995bd4dcc5c75091 upstream.

[BUG]
It's easy to trigger NULL pointer dereference, just by removing a
non-existing device id:

 # mkfs.btrfs -f -m single -d single /dev/test/scratch1 \
				     /dev/test/scratch2
 # mount /dev/test/scratch1 /mnt/btrfs
 # btrfs device remove 3 /mnt/btrfs

Then we have the following kernel NULL pointer dereference:

 BUG: kernel NULL pointer dereference, address: 0000000000000000
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: 0000 [#1] PREEMPT SMP NOPTI
 CPU: 9 PID: 649 Comm: btrfs Not tainted 5.14.0-rc3-custom+ #35
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
 RIP: 0010:btrfs_rm_device+0x4de/0x6b0 [btrfs]
  btrfs_ioctl+0x18bb/0x3190 [btrfs]
  ? lock_is_held_type+0xa5/0x120
  ? find_held_lock.constprop.0+0x2b/0x80
  ? do_user_addr_fault+0x201/0x6a0
  ? lock_release+0xd2/0x2d0
  ? __x64_sys_ioctl+0x83/0xb0
  __x64_sys_ioctl+0x83/0xb0
  do_syscall_64+0x3b/0x90
  entry_SYSCALL_64_after_hwframe+0x44/0xae

[CAUSE]
Commit a27a94c2b0c7 ("btrfs: Make btrfs_find_device_by_devspec return
btrfs_device directly") moves the "missing" device path check into
btrfs_rm_device().

But btrfs_rm_device() itself can have case where it only receives
@devid, with NULL as @device_path.

In that case, calling strcmp() on NULL will trigger the NULL pointer
dereference.

Before that commit, we handle the "missing" case inside
btrfs_find_device_by_devspec(), which will not check @device_path at all
if @devid is provided, thus no way to trigger the bug.

[FIX]
Before calling strcmp(), also make sure @device_path is not NULL.

Fixes: a27a94c2b0c7 ("btrfs: Make btrfs_find_device_by_devspec return btrfs_device directly")
CC: stable@vger.kernel.org # 5.4+
Reported-by: butt3rflyh4ck 
Reviewed-by: Anand Jain 
Signed-off-by: Qu Wenruo 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba 
Signed-off-by: Greg Kroah-Hartman

btrfs: fix race between marking inode needs to be logged and log syncing

2021-09-03T08:08:15+00:00

commit bc0939fcfab0d7efb2ed12896b1af3d819954a14 upstream.

We have a race between marking that an inode needs to be logged, either
at btrfs_set_inode_last_trans() or at btrfs_page_mkwrite(), and between
btrfs_sync_log(). The following steps describe how the race happens.

1) We are at transaction N;

2) Inode I was previously fsynced in the current transaction so it has:

    inode->logged_trans set to N;

3) The inode's root currently has:

   root->log_transid set to 1
   root->last_log_commit set to 0

   Which means only one log transaction was committed to far, log
   transaction 0. When a log tree is created we set ->log_transid and
   ->last_log_commit of its parent root to 0 (at btrfs_add_log_tree());

4) One more range of pages is dirtied in inode I;

5) Some task A starts an fsync against some other inode J (same root), and
   so it joins log transaction 1.

   Before task A calls btrfs_sync_log()...

6) Task B starts an fsync against inode I, which currently has the full
   sync flag set, so it starts delalloc and waits for the ordered extent
   to complete before calling btrfs_inode_in_log() at btrfs_sync_file();

7) During ordered extent completion we have btrfs_update_inode() called
   against inode I, which in turn calls btrfs_set_inode_last_trans(),
   which does the following:

     spin_lock(&inode->lock);
     inode->last_trans = trans->transaction->transid;
     inode->last_sub_trans = inode->root->log_transid;
     inode->last_log_commit = inode->root->last_log_commit;
     spin_unlock(&inode->lock);

   So ->last_trans is set to N and ->last_sub_trans set to 1.
   But before setting ->last_log_commit...

8) Task A is at btrfs_sync_log():

   - it increments root->log_transid to 2
   - starts writeback for all log tree extent buffers
   - waits for the writeback to complete
   - writes the super blocks
   - updates root->last_log_commit to 1

   It's a lot of slow steps between updating root->log_transid and
   root->last_log_commit;

9) The task doing the ordered extent completion, currently at
   btrfs_set_inode_last_trans(), then finally runs:

     inode->last_log_commit = inode->root->last_log_commit;
     spin_unlock(&inode->lock);

   Which results in inode->last_log_commit being set to 1.
   The ordered extent completes;

10) Task B is resumed, and it calls btrfs_inode_in_log() which returns
    true because we have all the following conditions met:

    inode->logged_trans == N which matches fs_info->generation &&
    inode->last_subtrans (1) <= inode->last_log_commit (1) &&
    inode->last_subtrans (1) <= root->last_log_commit (1) &&
    list inode->extent_tree.modified_extents is empty

    And as a consequence we return without logging the inode, so the
    existing logged version of the inode does not point to the extent
    that was written after the previous fsync.

It should be impossible in practice for one task be able to do so much
progress in btrfs_sync_log() while another task is at
btrfs_set_inode_last_trans() right after it reads root->log_transid and
before it reads root->last_log_commit. Even if kernel preemption is enabled
we know the task at btrfs_set_inode_last_trans() can not be preempted
because it is holding the inode's spinlock.

However there is another place where we do the same without holding the
spinlock, which is in the memory mapped write path at:

  vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf)
  {
     (...)
     BTRFS_I(inode)->last_trans = fs_info->generation;
     BTRFS_I(inode)->last_sub_trans = BTRFS_I(inode)->root->log_transid;
     BTRFS_I(inode)->last_log_commit = BTRFS_I(inode)->root->last_log_commit;
     (...)

So with preemption happening after setting ->last_sub_trans and before
setting ->last_log_commit, it is less of a stretch to have another task
do enough progress at btrfs_sync_log() such that the task doing the memory
mapped write ends up with ->last_sub_trans and ->last_log_commit set to
the same value. It is still a big stretch to get there, as the task doing
btrfs_sync_log() has to start writeback, wait for its completion and write
the super blocks.

So fix this in two different ways:

1) For btrfs_set_inode_last_trans(), simply set ->last_log_commit to the
   value of ->last_sub_trans minus 1;

2) For btrfs_page_mkwrite() only set the inode's ->last_sub_trans, just
   like we do for buffered and direct writes at btrfs_file_write_iter(),
   which is all we need to make sure multiple writes and fsyncs to an
   inode in the same transaction never result in an fsync missing that
   the inode changed and needs to be logged. Turn this into a helper
   function and use it both at btrfs_page_mkwrite() and at
   btrfs_file_write_iter() - this also fixes the problem that at
   btrfs_page_mkwrite() we were setting those fields without the
   protection of the inode's spinlock.

This is an extremely unlikely race to happen in practice.

Signed-off-by: Filipe Manana 
Signed-off-by: David Sterba 
Signed-off-by: Anand Jain 
Signed-off-by: Greg Kroah-Hartman

mm, oom: make the calculation of oom badness more accurate

2021-09-03T08:08:12+00:00

[ Upstream commit 9066e5cfb73cdbcdbb49e87999482ab615e9fc76 ]

Recently we found an issue on our production environment that when memcg
oom is triggered the oom killer doesn't chose the process with largest
resident memory but chose the first scanned process.  Note that all
processes in this memcg have the same oom_score_adj, so the oom killer
should chose the process with largest resident memory.

Bellow is part of the oom info, which is enough to analyze this issue.
[7516987.983223] memory: usage 16777216kB, limit 16777216kB, failcnt 52843037
[7516987.983224] memory+swap: usage 16777216kB, limit 9007199254740988kB, failcnt 0
[7516987.983225] kmem: usage 301464kB, limit 9007199254740988kB, failcnt 0
[...]
[7516987.983293] [ pid ]   uid  tgid total_vm      rss pgtables_bytes swapents oom_score_adj name
[7516987.983510] [ 5740]     0  5740      257        1    32768        0          -998 pause
[7516987.983574] [58804]     0 58804     4594      771    81920        0          -998 entry_point.bas
[7516987.983577] [58908]     0 58908     7089      689    98304        0          -998 cron
[7516987.983580] [58910]     0 58910    16235     5576   163840        0          -998 supervisord
[7516987.983590] [59620]     0 59620    18074     1395   188416        0          -998 sshd
[7516987.983594] [59622]     0 59622    18680     6679   188416        0          -998 python
[7516987.983598] [59624]     0 59624  1859266     5161   548864        0          -998 odin-agent
[7516987.983600] [59625]     0 59625   707223     9248   983040        0          -998 filebeat
[7516987.983604] [59627]     0 59627   416433    64239   774144        0          -998 odin-log-agent
[7516987.983607] [59631]     0 59631   180671    15012   385024        0          -998 python3
[7516987.983612] [61396]     0 61396   791287     3189   352256        0          -998 client
[7516987.983615] [61641]     0 61641  1844642    29089   946176        0          -998 client
[7516987.983765] [ 9236]     0  9236     2642      467    53248        0          -998 php_scanner
[7516987.983911] [42898]     0 42898    15543      838   167936        0          -998 su
[7516987.983915] [42900]  1000 42900     3673      867    77824        0          -998 exec_script_vr2
[7516987.983918] [42925]  1000 42925    36475    19033   335872        0          -998 python
[7516987.983921] [57146]  1000 57146     3673      848    73728        0          -998 exec_script_J2p
[7516987.983925] [57195]  1000 57195   186359    22958   491520        0          -998 python2
[7516987.983928] [58376]  1000 58376   275764    14402   290816        0          -998 rosmaster
[7516987.983931] [58395]  1000 58395   155166     4449   245760        0          -998 rosout
[7516987.983935] [58406]  1000 58406 18285584  3967322 37101568        0          -998 data_sim
[7516987.984221] oom-kill:constraint=CONSTRAINT_MEMCG,nodemask=(null),cpuset=3aa16c9482ae3a6f6b78bda68a55d32c87c99b985e0f11331cddf05af6c4d753,mems_allowed=0-1,oom_memcg=/kubepods/podf1c273d3-9b36-11ea-b3df-246e9693c184,task_memcg=/kubepods/podf1c273d3-9b36-11ea-b3df-246e9693c184/1f246a3eeea8f70bf91141eeaf1805346a666e225f823906485ea0b6c37dfc3d,task=pause,pid=5740,uid=0
[7516987.984254] Memory cgroup out of memory: Killed process 5740 (pause) total-vm:1028kB, anon-rss:4kB, file-rss:0kB, shmem-rss:0kB
[7516988.092344] oom_reaper: reaped process 5740 (pause), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB

We can find that the first scanned process 5740 (pause) was killed, but
its rss is only one page.  That is because, when we calculate the oom
badness in oom_badness(), we always ignore the negtive point and convert
all of these negtive points to 1.  Now as oom_score_adj of all the
processes in this targeted memcg have the same value -998, the points of
these processes are all negtive value.  As a result, the first scanned
process will be killed.

The oom_socre_adj (-998) in this memcg is set by kubelet, because it is a
a Guaranteed pod, which has higher priority to prevent from being killed
by system oom.

To fix this issue, we should make the calculation of oom point more
accurate.  We can achieve it by convert the chosen_point from 'unsigned
long' to 'long'.

[cai@lca.pw: reported a issue in the previous version]
[mhocko@suse.com: fixed the issue reported by Cai]
[mhocko@suse.com: add the comment in proc_oom_score()]
[laoar.shao@gmail.com: v3]
  Link: http://lkml.kernel.org/r/1594396651-9931-1-git-send-email-laoar.shao@gmail.com

Signed-off-by: Yafang Shao 
Signed-off-by: Andrew Morton 
Tested-by: Naresh Kamboju 
Acked-by: Michal Hocko 
Cc: David Rientjes 
Cc: Qian Cai 
Link: http://lkml.kernel.org/r/1594309987-9919-1-git-send-email-laoar.shao@gmail.com
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

ovl: fix uninitialized pointer read in ovl_lookup_real_one()

2021-09-03T08:08:12+00:00

[ Upstream commit 580c610429b3994e8db24418927747cf28443cde ]

One error path can result in release_dentry_name_snapshot() being called
before "name" was initialized by take_dentry_name_snapshot().

Fix by moving the release_dentry_name_snapshot() to immediately after the
only use.

Reported-by: Colin Ian King 
Signed-off-by: Miklos Szeredi 
Signed-off-by: Sasha Levin