linux-cve-announce - CVE-2025-38347: f2fs: fix to do sanity check on ino and xnid

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Message-ID: <2025071036-CVE-2025-38347-0116@gregkh>
Date: Thu, 10 Jul 2025 10:15:55 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38347: f2fs: fix to do sanity check on ino and xnid

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

f2fs: fix to do sanity check on ino and xnid

syzbot reported a f2fs bug as below:

INFO: task syz-executor140:5308 blocked for more than 143 seconds.
      Not tainted 6.14.0-rc7-syzkaller-00069-g81e4f8d68c66 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor140 state:D stack:24016 pid:5308  tgid:5308  ppid:5306   task_flags:0x400140 flags:0x00000006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5378 [inline]
 __schedule+0x190e/0x4c90 kernel/sched/core.c:6765
 __schedule_loop kernel/sched/core.c:6842 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6857
 io_schedule+0x8d/0x110 kernel/sched/core.c:7690
 folio_wait_bit_common+0x839/0xee0 mm/filemap.c:1317
 __folio_lock mm/filemap.c:1664 [inline]
 folio_lock include/linux/pagemap.h:1163 [inline]
 __filemap_get_folio+0x147/0xb40 mm/filemap.c:1917
 pagecache_get_page+0x2c/0x130 mm/folio-compat.c:87
 find_get_page_flags include/linux/pagemap.h:842 [inline]
 f2fs_grab_cache_page+0x2b/0x320 fs/f2fs/f2fs.h:2776
 __get_node_page+0x131/0x11b0 fs/f2fs/node.c:1463
 read_xattr_block+0xfb/0x190 fs/f2fs/xattr.c:306
 lookup_all_xattrs fs/f2fs/xattr.c:355 [inline]
 f2fs_getxattr+0x676/0xf70 fs/f2fs/xattr.c:533
 __f2fs_get_acl+0x52/0x870 fs/f2fs/acl.c:179
 f2fs_acl_create fs/f2fs/acl.c:375 [inline]
 f2fs_init_acl+0xd7/0x9b0 fs/f2fs/acl.c:418
 f2fs_init_inode_metadata+0xa0f/0x1050 fs/f2fs/dir.c:539
 f2fs_add_inline_entry+0x448/0x860 fs/f2fs/inline.c:666
 f2fs_add_dentry+0xba/0x1e0 fs/f2fs/dir.c:765
 f2fs_do_add_link+0x28c/0x3a0 fs/f2fs/dir.c:808
 f2fs_add_link fs/f2fs/f2fs.h:3616 [inline]
 f2fs_mknod+0x2e8/0x5b0 fs/f2fs/namei.c:766
 vfs_mknod+0x36d/0x3b0 fs/namei.c:4191
 unix_bind_bsd net/unix/af_unix.c:1286 [inline]
 unix_bind+0x563/0xe30 net/unix/af_unix.c:1379
 __sys_bind_socket net/socket.c:1817 [inline]
 __sys_bind+0x1e4/0x290 net/socket.c:1848
 __do_sys_bind net/socket.c:1853 [inline]
 __se_sys_bind net/socket.c:1851 [inline]
 __x64_sys_bind+0x7a/0x90 net/socket.c:1851
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Let's dump and check metadata of corrupted inode, it shows its xattr_nid
is the same to its i_ino.

dump.f2fs -i 3 chaseyu.img.raw
i_xattr_nid                             [0x       3 : 3]

So that, during mknod in the corrupted directory, it tries to get and
lock inode page twice, result in deadlock.

- f2fs_mknod
 - f2fs_add_inline_entry
  - f2fs_get_inode_page --- lock dir's inode page
   - f2fs_init_acl
    - f2fs_acl_create(dir,..)
     - __f2fs_get_acl
      - f2fs_getxattr
       - lookup_all_xattrs
        - __get_node_page --- try to lock dir's inode page

In order to fix this, let's add sanity check on ino and xnid.

The Linux kernel CVE team has assigned CVE-2025-38347 to this issue.


Affected and fixed versions
===========================

	Fixed in 6.6.95 with commit aaddc6c696bd1bff20eaacfa88579d6eae64d541
	Fixed in 6.12.35 with commit fed611bd8c7b76b070aa407d0c7558e20d9e1f68
	Fixed in 6.15.4 with commit 5a06d97d5340c00510f24e80e8de821bd3bd9285
	Fixed in 6.16-rc1 with commit 061cf3a84bde038708eb0f1d065b31b7c2456533

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-38347
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	fs/f2fs/inode.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/aaddc6c696bd1bff20eaacfa88579d6eae64d541
	https://git.kernel.org/stable/c/fed611bd8c7b76b070aa407d0c7558e20d9e1f68
	https://git.kernel.org/stable/c/5a06d97d5340c00510f24e80e8de821bd3bd9285
	https://git.kernel.org/stable/c/061cf3a84bde038708eb0f1d065b31b7c2456533