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| author | Ryusuke Konishi <konishi.ryusuke@gmail.com> | 2023-03-28 02:53:18 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-04-13 16:48:22 +0200 |
| commit | 92684e02654c91a61a0b0561433b710bcece19fe (patch) | |
| tree | 7678e87454143a7c3c8d6e8a032ae3a3576baecc | |
| parent | ba3a88b444cd6e99029d9a80da2e88bcd8362300 (diff) | |
| download | linux-stable-92684e02654c91a61a0b0561433b710bcece19fe.tar.gz linux-stable-92684e02654c91a61a0b0561433b710bcece19fe.tar.bz2 linux-stable-92684e02654c91a61a0b0561433b710bcece19fe.zip | |
nilfs2: fix potential UAF of struct nilfs_sc_info in nilfs_segctor_thread()
commit 6be49d100c22ffea3287a4b19d7639d259888e33 upstream.
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 <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/nilfs2/segment.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c index 6d21f9bc6de1..a276a2d236ed 100644 --- a/fs/nilfs2/segment.c +++ b/fs/nilfs2/segment.c @@ -2609,11 +2609,10 @@ static int nilfs_segctor_thread(void *arg) goto loop; end_thread: - spin_unlock(&sci->sc_state_lock); - /* end sync. */ sci->sc_task = NULL; wake_up(&sci->sc_wait_task); /* for nilfs_segctor_kill_thread() */ + spin_unlock(&sci->sc_state_lock); return 0; } |