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linux-stable/fs/overlayfs
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Jiachen Zhang a7573260ad 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>
2022-08-25 11:17:23 +02:00
..
copy_up.c ovl: fix missing revert_creds() on error path 2021-05-14 09:44:16 +02:00
dir.c ovl: fix warning in ovl_create_real() 2021-12-22 09:29:40 +01:00
export.c ovl: drop WARN_ON() dentry is NULL in ovl_encode_fh() 2022-08-25 11:17:23 +02:00
file.c ovl: fix deadlock in splice write 2021-11-17 09:48:49 +01:00
inode.c ovl: perform vfs_getxattr() with mounter creds 2021-02-17 10:35:15 +01:00
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
namei.c ovl: fix lookup failure on multi lower squashfs 2019-12-17 19:56:10 +01:00
overlayfs.h ovl: fix warning in ovl_create_real() 2021-12-22 09:29:40 +01:00
ovl_entry.h ovl: fix lookup failure on multi lower squashfs 2019-12-17 19:56:10 +01:00
readdir.c ovl: fix wrong WARN_ON() in ovl_cache_update_ino() 2020-02-11 04:35:24 -08:00
super.c ovl: fix warning in ovl_create_real() 2021-12-22 09:29:40 +01:00
util.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00