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linux-stable/fs/overlayfs
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Jiachen Zhang 35ef2ee74d ovl: drop WARN_ON() dentry is NULL in ovl_encode_fh() 
commit dd524b7f31 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: 8ed5eec9d6 ("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 14:22:51 +02:00
..
copy_up.c ovl: fix NULL pointer dereference in copy up warning 2022-02-05 12:38:59 +01:00
dir.c ovl: fix warning in ovl_create_real() 2021-12-22 09:32:50 +01:00
export.c ovl: drop WARN_ON() dentry is NULL in ovl_encode_fh() 2022-08-17 14:22:51 +02:00
file.c ovl: fix use after free in struct ovl_aio_req 2021-11-18 19:16:04 +01:00
inode.c ovl: fix filattr copy-up failure 2021-11-18 19:16:04 +01:00
Kconfig docs: fix broken references to text files 2020-04-20 15:35:59 -06:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
namei.c ovl: relax lookup error on mismatch origin ftype 2021-08-17 11:47:44 +02:00
overlayfs.h ovl: fix warning in ovl_create_real() 2021-12-22 09:32:50 +01:00
ovl_entry.h ovl: implement volatile-specific fsync error behaviour 2021-01-28 10:22:48 +01:00
readdir.c ovl: skip stale entries in merge dir cache iteration 2021-08-10 10:21:30 +02:00
super.c fs: add is_idmapped_mnt() helper 2022-07-02 16:41:14 +02:00
util.c ovl: consistent behavior for immutable/append-only inodes 2021-08-17 11:47:43 +02:00