Jiachen Zhang 247caf4a87 ovl: drop WARN_ON() dentry is NULL in ovl_encode_fh()
commit dd524b7f317de8d31d638cbfdc7be4cf9b770e42 upstream.

Some code paths cannot guarantee the inode have any dentry alias. So
WARN_ON() all !dentry may flood the kernel logs.

For example, when an overlayfs inode is watched by inotifywait (1), and
someone is trying to read the /proc/$(pidof inotifywait)/fdinfo/INOTIFY_FD,
at that time if the dentry has been reclaimed by kernel (such as
echo 2 > /proc/sys/vm/drop_caches), there will be a WARN_ON(). The
printed call stack would be like:

    ? show_mark_fhandle+0xf0/0xf0
    show_mark_fhandle+0x4a/0xf0
    ? show_mark_fhandle+0xf0/0xf0
    ? seq_vprintf+0x30/0x50
    ? seq_printf+0x53/0x70
    ? show_mark_fhandle+0xf0/0xf0
    inotify_fdinfo+0x70/0x90
    show_fdinfo.isra.4+0x53/0x70
    seq_show+0x130/0x170
    seq_read+0x153/0x440
    vfs_read+0x94/0x150
    ksys_read+0x5f/0xe0
    do_syscall_64+0x59/0x1e0
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

So let's drop WARN_ON() to avoid kernel log flooding.

Reported-by: Hongbo Yin <yinhongbo@bytedance.com>
Signed-off-by: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>
Signed-off-by: Tianci Zhang <zhangtianci.1997@bytedance.com>
Fixes: 8ed5eec9d6c4 ("ovl: encode pure upper file handles")
Cc: <stable@vger.kernel.org> # v4.16
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-08-17 15:13:48 +02:00
..
2022-06-17 06:03:30 +09:00
2022-05-09 16:21:44 -04:00
2022-05-09 16:21:45 -04:00
2022-07-16 13:48:55 -07:00
2022-05-09 16:21:45 -04:00
2022-05-02 11:23:49 -05:00
2022-06-01 11:54:29 -07:00
2022-06-03 10:34:34 -07:00
2022-05-27 15:49:30 -07:00
2022-05-24 19:55:07 -07:00
2022-05-09 16:21:45 -04:00
2022-05-24 19:55:07 -07:00
2022-06-03 16:57:16 -07:00
2022-05-09 23:12:53 -04:00
2022-05-09 16:21:46 -04:00
2022-05-23 20:24:12 -05:00
2022-05-24 19:55:07 -07:00
2022-05-24 19:55:07 -07:00
2022-05-24 19:55:07 -07:00
2022-03-28 17:29:53 -07:00
2022-05-27 15:49:30 -07:00
2022-05-09 18:20:49 -07:00
2022-06-04 18:52:00 -07:00
2022-04-01 19:35:56 -07:00
2022-04-19 10:19:02 -07:00
2022-05-22 21:03:01 +01:00
2022-04-17 19:49:59 -06:00