linux.git/fs/nilfs2/segment.c, branch v6.3

nilfs2: initialize unused bytes in segment summary blocks

2023-04-18T21:22:14+00:00

Syzbot still reports uninit-value in nilfs_add_checksums_on_logs() for
KMSAN enabled kernels after applying commit 7397031622e0 ("nilfs2:
initialize "struct nilfs_binfo_dat"->bi_pad field").

This is because the unused bytes at the end of each block in segment
summaries are not initialized.  So this fixes the issue by padding the
unused bytes with null bytes.

Link: https://lkml.kernel.org/r/20230417173513.12598-1-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi 
Tested-by: Ryusuke Konishi 
Reported-by: syzbot+048585f3f4227bb2b49b@syzkaller.appspotmail.com
  Link: https://syzkaller.appspot.com/bug?extid=048585f3f4227bb2b49b
Cc: Alexander Potapenko 
Cc: 
Signed-off-by: Andrew Morton

nilfs2: fix potential UAF of struct nilfs_sc_info in nilfs_segctor_thread()

2023-04-06T01:06:23+00:00

The finalization of nilfs_segctor_thread() can race with
nilfs_segctor_kill_thread() which terminates that thread, potentially
causing a use-after-free BUG as KASAN detected.

At the end of nilfs_segctor_thread(), it assigns NULL to "sc_task" member
of "struct nilfs_sc_info" to indicate the thread has finished, and then
notifies nilfs_segctor_kill_thread() of this using waitqueue
"sc_wait_task" on the struct nilfs_sc_info.

However, here, immediately after the NULL assignment to "sc_task", it is
possible that nilfs_segctor_kill_thread() will detect it and return to
continue the deallocation, freeing the nilfs_sc_info structure before the
thread does the notification.

This fixes the issue by protecting the NULL assignment to "sc_task" and
its notification, with spinlock "sc_state_lock" of the struct
nilfs_sc_info.  Since nilfs_segctor_kill_thread() does a final check to
see if "sc_task" is NULL with "sc_state_lock" locked, this can eliminate
the race.

Link: https://lkml.kernel.org/r/20230327175318.8060-1-konishi.ryusuke@gmail.com
Reported-by: syzbot+b08ebcc22f8f3e6be43a@syzkaller.appspotmail.com
Link: https://lkml.kernel.org/r/00000000000000660d05f7dfa877@google.com
Signed-off-by: Ryusuke Konishi 
Cc: 
Signed-off-by: Andrew Morton

nilfs2: convert nilfs_lookup_dirty_node_buffers() to use filemap_get_folios_tag()

2023-02-03T06:33:17+00:00

Convert function to use folios throughout.  This is in preparation for the
removal of find_get_pages_range_tag().  This change removes 1 call to
compound_head().

Link: https://lkml.kernel.org/r/20230104211448.4804-20-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) 
Acked-by: Ryusuke Konishi 
Signed-off-by: Andrew Morton

nilfs2: convert nilfs_lookup_dirty_data_buffers() to use filemap_get_folios_tag()

2023-02-03T06:33:17+00:00

Convert function to use folios throughout. This is in preparation for
the removal of find_get_pages_range_tag(). This change removes 4 calls
to compound_head().

Link: https://lkml.kernel.org/r/20230104211448.4804-19-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) 
Acked-by: Ryusuke Konishi 
Signed-off-by: Andrew Morton

nilfs2: replace obvious uses of b_page with b_folio

2023-01-19T01:12:41+00:00

These places just use b_page to get to the buffer's address_space or the
index of the page the buffer is in.

Link: https://lkml.kernel.org/r/20221215214402.3522366-11-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Reviewed-by: Jan Kara 
Signed-off-by: Andrew Morton

treewide: Convert del_timer() to timer_shutdown()

2022-12-25T21:38:09+00:00

Due to several bugs caused by timers being re-armed after they are
shutdown and just before they are freed, a new state of timers was added
called "shutdown".  After a timer is set to this state, then it can no
longer be re-armed.

The following script was run to find all the trivial locations where
del_timer() or del_timer_sync() is called in the same function that the
object holding the timer is freed.  It also ignores any locations where
the timer->function is modified between the del_timer*() and the free(),
as that is not considered a "trivial" case.

This was created by using a coccinelle script and the following
commands:

    $ cat timer.cocci
    @@
    expression ptr, slab;
    identifier timer, rfield;
    @@
    (
    -       del_timer(&ptr->timer);
    +       timer_shutdown(&ptr->timer);
    |
    -       del_timer_sync(&ptr->timer);
    +       timer_shutdown_sync(&ptr->timer);
    )
      ... when strict
          when != ptr->timer
    (
            kfree_rcu(ptr, rfield);
    |
            kmem_cache_free(slab, ptr);
    |
            kfree(ptr);
    )

    $ spatch timer.cocci . > /tmp/t.patch
    $ patch -p1 < /tmp/t.patch

Link: https://lore.kernel.org/lkml/20221123201306.823305113@linutronix.de/
Signed-off-by: Steven Rostedt (Google) 
Acked-by: Pavel Machek  [ LED ]
Acked-by: Kalle Valo  [ wireless ]
Acked-by: Paolo Abeni  [ networking ]
Signed-off-by: Linus Torvalds

nilfs2: fix use-after-free bug of ns_writer on remount

2022-11-08T23:57:24+00:00

If a nilfs2 filesystem is downgraded to read-only due to metadata
corruption on disk and is remounted read/write, or if emergency read-only
remount is performed, detaching a log writer and synchronizing the
filesystem can be done at the same time.

In these cases, use-after-free of the log writer (hereinafter
nilfs->ns_writer) can happen as shown in the scenario below:

 Task1                               Task2
 --------------------------------    ------------------------------
 nilfs_construct_segment
   nilfs_segctor_sync
     init_wait
     init_waitqueue_entry
     add_wait_queue
     schedule
                                     nilfs_remount (R/W remount case)
				       nilfs_attach_log_writer
                                         nilfs_detach_log_writer
                                           nilfs_segctor_destroy
                                             kfree
     finish_wait
       _raw_spin_lock_irqsave
         __raw_spin_lock_irqsave
           do_raw_spin_lock
             debug_spin_lock_before  <-- use-after-free

While Task1 is sleeping, nilfs->ns_writer is freed by Task2.  After Task1
waked up, Task1 accesses nilfs->ns_writer which is already freed.  This
scenario diagram is based on the Shigeru Yoshida's post [1].

This patch fixes the issue by not detaching nilfs->ns_writer on remount so
that this UAF race doesn't happen.  Along with this change, this patch
also inserts a few necessary read-only checks with superblock instance
where only the ns_writer pointer was used to check if the filesystem is
read-only.

Link: https://syzkaller.appspot.com/bug?id=79a4c002e960419ca173d55e863bd09e8112df8b
Link: https://lkml.kernel.org/r/20221103141759.1836312-1-syoshida@redhat.com [1]
Link: https://lkml.kernel.org/r/20221104142959.28296-1-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi 
Reported-by: syzbot+f816fa82f8783f7a02bb@syzkaller.appspotmail.com
Reported-by: Shigeru Yoshida 
Tested-by: Ryusuke Konishi 
Cc: 
Signed-off-by: Andrew Morton

Merge tag 'mm-hotfixes-stable-2022-10-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-10-12T18:16:58+00:00

Pull misc hotfixes from Andrew Morton:
 "Five hotfixes - three for nilfs2, two for MM. For are cc:stable, one
  is not"

* tag 'mm-hotfixes-stable-2022-10-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  nilfs2: fix leak of nilfs_root in case of writer thread creation failure
  nilfs2: fix NULL pointer dereference at nilfs_bmap_lookup_at_level()
  nilfs2: fix use-after-free bug of struct nilfs_root
  mm/damon/core: initialize damon_target->list in damon_new_target()
  mm/hugetlb: fix races when looking up a CONT-PTE/PMD size hugetlb page

nilfs2: fix leak of nilfs_root in case of writer thread creation failure

2022-10-12T02:05:45+00:00

If nilfs_attach_log_writer() failed to create a log writer thread, it
frees a data structure of the log writer without any cleanup.  After
commit e912a5b66837 ("nilfs2: use root object to get ifile"), this causes
a leak of struct nilfs_root, which started to leak an ifile metadata inode
and a kobject on that struct.

In addition, if the kernel is booted with panic_on_warn, the above
ifile metadata inode leak will cause the following panic when the
nilfs2 kernel module is removed:

  kmem_cache_destroy nilfs2_inode_cache: Slab cache still has objects when
  called from nilfs_destroy_cachep+0x16/0x3a [nilfs2]
  WARNING: CPU: 8 PID: 1464 at mm/slab_common.c:494 kmem_cache_destroy+0x138/0x140
  ...
  RIP: 0010:kmem_cache_destroy+0x138/0x140
  Code: 00 20 00 00 e8 a9 55 d8 ff e9 76 ff ff ff 48 8b 53 60 48 c7 c6 20 70 65 86 48 c7 c7 d8 69 9c 86 48 8b 4c 24 28 e8 ef 71 c7 00 <0f> 0b e9 53 ff ff ff c3 48 81 ff ff 0f 00 00 77 03 31 c0 c3 53 48
  ...
  Call Trace:
   
   ? nilfs_palloc_freev.cold.24+0x58/0x58 [nilfs2]
   nilfs_destroy_cachep+0x16/0x3a [nilfs2]
   exit_nilfs_fs+0xa/0x1b [nilfs2]
    __x64_sys_delete_module+0x1d9/0x3a0
   ? __sanitizer_cov_trace_pc+0x1a/0x50
   ? syscall_trace_enter.isra.19+0x119/0x190
   do_syscall_64+0x34/0x80
   entry_SYSCALL_64_after_hwframe+0x63/0xcd
   ...
   
  Kernel panic - not syncing: panic_on_warn set ...

This patch fixes these issues by calling nilfs_detach_log_writer() cleanup
function if spawning the log writer thread fails.

Link: https://lkml.kernel.org/r/20221007085226.57667-1-konishi.ryusuke@gmail.com
Fixes: e912a5b66837 ("nilfs2: use root object to get ifile")
Signed-off-by: Ryusuke Konishi 
Reported-by: syzbot+7381dc4ad60658ca4c05@syzkaller.appspotmail.com
Tested-by: Ryusuke Konishi 
Cc: 
Signed-off-by: Andrew Morton

nilfs2: replace WARN_ONs by nilfs_error for checkpoint acquisition failure

2022-10-12T01:51:10+00:00

If creation or finalization of a checkpoint fails due to anomalies in the
checkpoint metadata on disk, a kernel warning is generated.

This patch replaces the WARN_ONs by nilfs_error, so that a kernel, booted
with panic_on_warn, does not panic.  A nilfs_error is appropriate here to
handle the abnormal filesystem condition.

This also replaces the detected error codes with an I/O error so that
neither of the internal error codes is returned to callers.

Link: https://lkml.kernel.org/r/20220929123330.19658-1-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi 
Reported-by: syzbot+fbb3e0b24e8dae5a16ee@syzkaller.appspotmail.com
Signed-off-by: Andrew Morton