linux-stable.git/fs, branch v4.4.207

CIFS: Respect O_SYNC and O_DIRECT flags during reconnect

2019-12-21T09:35:44+00:00

commit 44805b0e62f15e90d233485420e1847133716bdc upstream.

Currently the client translates O_SYNC and O_DIRECT flags
into corresponding SMB create options when openning a file.
The problem is that on reconnect when the file is being
re-opened the client doesn't set those flags and it causes
a server to reject re-open requests because create options
don't match. The latter means that any subsequent system
call against that open file fail until a share is re-mounted.

Fix this by properly setting SMB create options when
re-openning files after reconnects.

Fixes: 1013e760d10e6: ("SMB3: Don't ignore O_SYNC/O_DSYNC and O_DIRECT flags")
Cc: Stable 
Signed-off-by: Pavel Shilovsky 
Signed-off-by: Steve French 
Signed-off-by: Greg Kroah-Hartman

Btrfs: fix negative subv_writers counter and data space leak after buffered write

2019-12-21T09:35:32+00:00

[ Upstream commit a0e248bb502d5165b3314ac3819e888fdcdf7d9f ]

When doing a buffered write it's possible to leave the subv_writers
counter of the root, used for synchronization between buffered nocow
writers and snapshotting. This happens in an exceptional case like the
following:

1) We fail to allocate data space for the write, since there's not
   enough available data space nor enough unallocated space for allocating
   a new data block group;

2) Because of that failure, we try to go to NOCOW mode, which succeeds
   and therefore we set the local variable 'only_release_metadata' to true
   and set the root's sub_writers counter to 1 through the call to
   btrfs_start_write_no_snapshotting() made by check_can_nocow();

3) The call to btrfs_copy_from_user() returns zero, which is very unlikely
   to happen but not impossible;

4) No pages are copied because btrfs_copy_from_user() returned zero;

5) We call btrfs_end_write_no_snapshotting() which decrements the root's
   subv_writers counter to 0;

6) We don't set 'only_release_metadata' back to 'false' because we do
   it only if 'copied', the value returned by btrfs_copy_from_user(), is
   greater than zero;

7) On the next iteration of the while loop, which processes the same
   page range, we are now able to allocate data space for the write (we
   got enough data space released in the meanwhile);

8) After this if we fail at btrfs_delalloc_reserve_metadata(), because
   now there isn't enough free metadata space, or in some other place
   further below (prepare_pages(), lock_and_cleanup_extent_if_need(),
   btrfs_dirty_pages()), we break out of the while loop with
   'only_release_metadata' having a value of 'true';

9) Because 'only_release_metadata' is 'true' we end up decrementing the
   root's subv_writers counter to -1 (through a call to
   btrfs_end_write_no_snapshotting()), and we also end up not releasing the
   data space previously reserved through btrfs_check_data_free_space().
   As a consequence the mechanism for synchronizing NOCOW buffered writes
   with snapshotting gets broken.

Fix this by always setting 'only_release_metadata' to false at the start
of each iteration.

Fixes: 8257b2dc3c1a ("Btrfs: introduce btrfs_{start, end}_nocow_write() for each subvolume")
Fixes: 7ee9e4405f26 ("Btrfs: check if we can nocow if we don't have data space")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik 
Signed-off-by: Filipe Manana 
Reviewed-by: David Sterba 
Signed-off-by: David Sterba 
Signed-off-by: Sasha Levin

quota: fix livelock in dquot_writeback_dquots

2019-12-21T09:35:30+00:00

commit 6ff33d99fc5c96797103b48b7b0902c296f09c05 upstream.

Write only quotas which are dirty at entry.

XFSTEST: https://github.com/dmonakhov/xfstests/commit/b10ad23566a5bf75832a6f500e1236084083cddc

Link: https://lore.kernel.org/r/20191031103920.3919-1-dmonakhov@openvz.org
CC: stable@vger.kernel.org
Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Dmitry Monakhov 
Signed-off-by: Jan Kara 
Signed-off-by: Greg Kroah-Hartman

quota: Check that quota is not dirty before release

2019-12-21T09:35:30+00:00

commit df4bb5d128e2c44848aeb36b7ceceba3ac85080d upstream.

There is a race window where quota was redirted once we drop dq_list_lock inside dqput(),
but before we grab dquot->dq_lock inside dquot_release()

TASK1                                                       TASK2 (chowner)
->dqput()
  we_slept:
    spin_lock(&dq_list_lock)
    if (dquot_dirty(dquot)) {
          spin_unlock(&dq_list_lock);
          dquot->dq_sb->dq_op->write_dquot(dquot);
          goto we_slept
    if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
          spin_unlock(&dq_list_lock);
          dquot->dq_sb->dq_op->release_dquot(dquot);
                                                            dqget()
							    mark_dquot_dirty()
							    dqput()
          goto we_slept;
        }
So dquot dirty quota will be released by TASK1, but on next we_sleept loop
we detect this and call ->write_dquot() for it.
XFSTEST: https://github.com/dmonakhov/xfstests/commit/440a80d4cbb39e9234df4d7240aee1d551c36107

Link: https://lore.kernel.org/r/20191031103920.3919-2-dmonakhov@openvz.org
CC: stable@vger.kernel.org
Signed-off-by: Dmitry Monakhov 
Signed-off-by: Jan Kara 
Signed-off-by: Greg Kroah-Hartman

btrfs: Remove btrfs_bio::flags member

2019-12-21T09:35:19+00:00

commit 34b127aecd4fe8e6a3903e10f204a7b7ffddca22 upstream.

The last user of btrfs_bio::flags was removed in commit 326e1dbb5736
("block: remove management of bi_remaining when restoring original
bi_end_io"), remove it.

(Tagged for stable as the structure is heavily used and space savings
are desirable.)

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

btrfs: check page->mapping when loading free space cache

2019-12-21T09:35:19+00:00

commit 3797136b626ad4b6582223660c041efdea8f26b2 upstream.

While testing 5.2 we ran into the following panic

[52238.017028] BUG: kernel NULL pointer dereference, address: 0000000000000001
[52238.105608] RIP: 0010:drop_buffers+0x3d/0x150
[52238.304051] Call Trace:
[52238.308958]  try_to_free_buffers+0x15b/0x1b0
[52238.317503]  shrink_page_list+0x1164/0x1780
[52238.325877]  shrink_inactive_list+0x18f/0x3b0
[52238.334596]  shrink_node_memcg+0x23e/0x7d0
[52238.342790]  ? do_shrink_slab+0x4f/0x290
[52238.350648]  shrink_node+0xce/0x4a0
[52238.357628]  balance_pgdat+0x2c7/0x510
[52238.365135]  kswapd+0x216/0x3e0
[52238.371425]  ? wait_woken+0x80/0x80
[52238.378412]  ? balance_pgdat+0x510/0x510
[52238.386265]  kthread+0x111/0x130
[52238.392727]  ? kthread_create_on_node+0x60/0x60
[52238.401782]  ret_from_fork+0x1f/0x30

The page we were trying to drop had a page->private, but had no
page->mapping and so called drop_buffers, assuming that we had a
buffer_head on the page, and then panic'ed trying to deref 1, which is
our page->private for data pages.

This is happening because we're truncating the free space cache while
we're trying to load the free space cache.  This isn't supposed to
happen, and I'll fix that in a followup patch.  However we still
shouldn't allow those sort of mistakes to result in messing with pages
that do not belong to us.  So add the page->mapping check to verify that
we still own this page after dropping and re-acquiring the page lock.

This page being unlocked as:
btrfs_readpage
  extent_read_full_page
    __extent_read_full_page
      __do_readpage
        if (!nr)
	   unlock_page  <-- nr can be 0 only if submit_extent_page
			    returns an error

CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana 
Reviewed-by: Nikolay Borisov 
Signed-off-by: Josef Bacik 
[ add callchain ]
Signed-off-by: David Sterba 
Signed-off-by: Greg Kroah-Hartman

fs/proc/array.c: allow reporting eip/esp for all coredumping threads

2019-12-21T09:35:07+00:00

commit cb8f381f1613cafe3aec30809991cd56e7135d92 upstream.

0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in /proc/PID/stat")
stopped reporting eip/esp and fd7d56270b52 ("fs/proc: Report eip/esp in
/prod/PID/stat for coredumping") reintroduced the feature to fix a
regression with userspace core dump handlers (such as minicoredumper).

Because PF_DUMPCORE is only set for the primary thread, this didn't fix
the original problem for secondary threads.  Allow reporting the eip/esp
for all threads by checking for PF_EXITING as well.  This is set for all
the other threads when they are killed.  coredump_wait() waits for all the
tasks to become inactive before proceeding to invoke a core dumper.

Link: http://lkml.kernel.org/r/87y32p7i7a.fsf@linutronix.de
Link: http://lkml.kernel.org/r/20190522161614.628-1-jlu@pengutronix.de
Fixes: fd7d56270b526ca3 ("fs/proc: Report eip/esp in /prod/PID/stat for coredumping")
Signed-off-by: John Ogness 
Reported-by: Jan Luebbe 
Tested-by: Jan Luebbe 
Cc: Alexey Dobriyan 
Cc: Andy Lutomirski 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: zhangyi (F) 
Signed-off-by: Greg Kroah-Hartman

proc: fix coredump vs read /proc/*/stat race

2019-12-21T09:35:06+00:00

commit 8bb2ee192e482c5d500df9f2b1b26a560bd3026f upstream.

do_task_stat() accesses IP and SP of a task without bumping reference
count of a stack (which became an entity with independent lifetime at
some point).

Steps to reproduce:

    #include 
    #include 
    #include 
    #include 
    #include 
    #include 
    #include 
    #include 

    int main(void)
    {
    	setrlimit(RLIMIT_CORE, &(struct rlimit){});

    	while (1) {
    		char buf[64];
    		char buf2[4096];
    		pid_t pid;
    		int fd;

    		pid = fork();
    		if (pid == 0) {
    			*(volatile int *)0 = 0;
    		}

    		snprintf(buf, sizeof(buf), "/proc/%u/stat", pid);
    		fd = open(buf, O_RDONLY);
    		read(fd, buf2, sizeof(buf2));
    		close(fd);

    		waitpid(pid, NULL, 0);
    	}
    	return 0;
    }

    BUG: unable to handle kernel paging request at 0000000000003fd8
    IP: do_task_stat+0x8b4/0xaf0
    PGD 800000003d73e067 P4D 800000003d73e067 PUD 3d558067 PMD 0
    Oops: 0000 [#1] PREEMPT SMP PTI
    CPU: 0 PID: 1417 Comm: a.out Not tainted 4.15.0-rc8-dirty #2
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1.fc27 04/01/2014
    RIP: 0010:do_task_stat+0x8b4/0xaf0
    Call Trace:
     proc_single_show+0x43/0x70
     seq_read+0xe6/0x3b0
     __vfs_read+0x1e/0x120
     vfs_read+0x84/0x110
     SyS_read+0x3d/0xa0
     entry_SYSCALL_64_fastpath+0x13/0x6c
    RIP: 0033:0x7f4d7928cba0
    RSP: 002b:00007ffddb245158 EFLAGS: 00000246
    Code: 03 b7 a0 01 00 00 4c 8b 4c 24 70 4c 8b 44 24 78 4c 89 74 24 18 e9 91 f9 ff ff f6 45 4d 02 0f 84 fd f7 ff ff 48 8b 45 40 48 89 ef <48> 8b 80 d8 3f 00 00 48 89 44 24 20 e8 9b 97 eb ff 48 89 44 24
    RIP: do_task_stat+0x8b4/0xaf0 RSP: ffffc90000607cc8
    CR2: 0000000000003fd8

John Ogness said: for my tests I added an else case to verify that the
race is hit and correctly mitigated.

Link: http://lkml.kernel.org/r/20180116175054.GA11513@avx2
Signed-off-by: Alexey Dobriyan 
Reported-by: "Kohli, Gaurav" 
Tested-by: John Ogness 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Oleg Nesterov 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: zhangyi (F) 
Signed-off-by: Greg Kroah-Hartman

fs/proc: Report eip/esp in /prod/PID/stat for coredumping

2019-12-21T09:35:06+00:00

commit fd7d56270b526ca3ed0c224362e3c64a0f86687a upstream.

Commit 0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in
/proc/PID/stat") stopped reporting eip/esp because it is
racy and dangerous for executing tasks. The comment adds:

    As far as I know, there are no use programs that make any
    material use of these fields, so just get rid of them.

However, existing userspace core-dump-handler applications (for
example, minicoredumper) are using these fields since they
provide an excellent cross-platform interface to these valuable
pointers. So that commit introduced a user space visible
regression.

Partially revert the change and make the readout possible for
tasks with the proper permissions and only if the target task
has the PF_DUMPCORE flag set.

Fixes: 0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in> /proc/PID/stat")
Reported-by: Marco Felsch 
Signed-off-by: John Ogness 
Reviewed-by: Andy Lutomirski 
Cc: Tycho Andersen 
Cc: Kees Cook 
Cc: Peter Zijlstra 
Cc: Brian Gerst 
Cc: stable@vger.kernel.org
Cc: Tetsuo Handa 
Cc: Borislav Petkov 
Cc: Al Viro 
Cc: Linux API 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Link: http://lkml.kernel.org/r/87poatfwg6.fsf@linutronix.de
Signed-off-by: Thomas Gleixner 
[ zhangyi: 68db0cf10678 does not merged, skip the task_stack.h for 4.4]
Signed-off-by: zhangyi (F) 
Signed-off-by: Greg Kroah-Hartman

fs/proc: Stop reporting eip and esp in /proc/PID/stat

2019-12-21T09:35:05+00:00

commit 0a1eb2d474edfe75466be6b4677ad84e5e8ca3f5 upstream.

Reporting these fields on a non-current task is dangerous.  If the
task is in any state other than normal kernel code, they may contain
garbage or even kernel addresses on some architectures.  (x86_64
used to do this.  I bet lots of architectures still do.)  With
CONFIG_THREAD_INFO_IN_TASK=y, it can OOPS, too.

As far as I know, there are no use programs that make any material
use of these fields, so just get rid of them.

Reported-by: Jann Horn 
Signed-off-by: Andy Lutomirski 
Acked-by: Thomas Gleixner 
Cc: Al Viro 
Cc: Andrew Morton 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Kees Cook 
Cc: Linus Torvalds 
Cc: Linux API 
Cc: Peter Zijlstra 
Cc: Tetsuo Handa 
Cc: Tycho Andersen 
Link: http://lkml.kernel.org/r/a5fed4c3f4e33ed25d4bb03567e329bc5a712bcc.1475257877.git.luto@kernel.org
Signed-off-by: Ingo Molnar 
Signed-off-by: zhangyi (F) 
Signed-off-by: Greg Kroah-Hartman