[CVE-2022-50346][MODERATE REGULAR] ext4: init quota for 'old.inode' in 'ext4_rename'

[CVE-2022-50346][MODERATE REGULAR] ext4: init quota for 'old.inode' in 'ext4_rename'

[AL-KERNEL]

CVE: CVE-2022-50346
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ext4: init quota for 'old.inode' in 'ext4_rename'
Commit: 67f6d5a4043f3db0c6bb0e14a0d97a7be8bfb8b5
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=67f6d5a4043f3db0c6bb0e14a0d97a7be8bfb8b5
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2022-50346
Analysis date: Wed, 03 Jun 2026 10:51:11 -0400
ActionableScore: 4
ActionableScore lower bound: 2
Actionable bucket: Borderline Moderate, but likely auto-close candidate after normal validation
Manual review required: NO

Summary:
A local ext4 rename operation can dirty old.inode and trigger extra_isize or xattr block allocation before quota initialization, causing a kernel warning and possible local DoS on panic_on_warn systems, without evidence of memory corruption or privilege escalation.

======================================================================
ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2022-50346 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2022-50346

The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.

The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.

Published priority for this report: MODERATE REGULAR
Manual review required: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2022-50346	MODERATE	CHECK	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H';CWE-665;CWE-754;CWE-703;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.3';DESCR 'ext4_rename can dirty old.inode and trigger extra_isize expansion before quota state for that inode is initialized. Under specific ext4 quota and inode layout conditions this can reach xattr block allocation with missing quota initialization and cause a kernel warning in ext4_xattr_block_set. For the CVSS the PR:L is used because a local user or process must be able to perform rename operations on an affected ext4 mount. The issue is not network reachable and there is no clear UAF, OOB write, or arbitrary write primitive in the patch context. Impact is mainly local denial of service via warning or panic_on_warn, with only limited integrity concern for quota accounting in the paranoid interpretation.';NO MANUAL CHECK; ,and ActionableScore result is Borderline Moderate, but likely auto-close candidate after normal validation (with actual score 3) 	MAYBE	DANGER DISK INIT HARDWARE CVEOUTDATED SYZBOT  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	checked

======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScoreLower=2
ActionableScore=4

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 4
* Final recommended bucket: **Borderline Moderate, but likely auto-close candidate after normal validation**

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1. A local user able to perform rename operations on an affected ext4 filesystem can reach ext4_rename.
* Important filesystem/storage path: +1. ext4 metadata, quota initialization, inode dirtying, and xattr expansion are involved.

Paranoid additional signals:

* Reliable kernel crash / strong DoS: +1. The observed impact is a kernel WARNING, which can become a crash on systems with panic_on_warn.
* Integrity impact plausible: +1. There is a limited quota/accounting correctness concern because block allocation may occur before quota initialization for old.inode.

Signals not applied:

* No generic memory corruption. The patch does not show UAF, double free, OOB write, heap overwrite, or arbitrary write.
* No privilege escalation signal. There is no demonstrated reclaim, object confusion, controlled overwrite, or credential/security-boundary primitive.
* No remote reachability. Trigger is local filesystem operation, not network input.
* No filesystem metadata corruption signal. The issue is a warning from missing quota initialization, not demonstrated persistent metadata corruption.

## 3. Reachability analysis

The bug is reachable by a local user or process that can perform rename on an affected ext4 mount. The path is not network reachable. Namespaces and containers may matter only if the container has access to an affected ext4-backed writable path, but this does not reduce the issue to PR:N because local code execution is still required. The triggering conditions are specific: quota handling must be relevant, old.inode must be dirtied during rename, and extra_isize expansion or xattr movement must allocate a block before quota initialization. This makes the issue more constrained than a typical ext4 metadata corruption bug.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like local filesystem DoS issue, not an Important-class vulnerability. The realistic impact is a kernel warning and possible crash only on panic_on_warn configurations. The paranoid interpretation can include limited integrity concern for quota accounting, but the patch context does not support memory corruption or practical privilege escalation.

## 5. One-sentence report phrase

A local ext4 rename operation can dirty old.inode and trigger extra_isize or xattr block allocation before quota initialization, causing a kernel warning and possible local DoS on panic_on_warn systems, without evidence of memory corruption or privilege escalation.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can likely be auto-closed after confirming affected kernel versions and ext4 quota configuration exposure. The issue lacks remote reachability, lacks a memory corruption primitive, and the main demonstrated impact is warning or local DoS.

======================================================================
UPSTREAM PATCH SUMMARY
======================================================================

Patch: ext4: init quota for 'old.inode' in 'ext4_rename'
Commit: 67f6d5a4043f3db0c6bb0e14a0d97a7be8bfb8b5
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=67f6d5a4043f3db0c6bb0e14a0d97a7be8bfb8b5

Commit description:

Syzbot found the following issue:
ext4_parse_param: s_want_extra_isize=128
ext4_inode_info_init: s_want_extra_isize=32
ext4_rename: old.inode=ffff88823869a2c8 old.dir=ffff888238699828 new.inode=ffff88823869d7e8 new.dir=ffff888238699828
__ext4_mark_inode_dirty: inode=ffff888238699828 ea_isize=32 want_ea_size=128
__ext4_mark_inode_dirty: inode=ffff88823869a2c8 ea_isize=32 want_ea_size=128
ext4_xattr_block_set: inode=ffff88823869a2c8
------------[ cut here ]------------
WARNING: CPU: 13 PID: 2234 at fs/ext4/xattr.c:2070 ext4_xattr_block_set.cold+0x22/0x980
Modules linked in:
RIP: 0010:ext4_xattr_block_set.cold+0x22/0x980
RSP: 0018:ffff888227d3f3b0 EFLAGS: 00010202
RAX: 0000000000000001 RBX: ffff88823007a000 RCX: 0000000000000000
RDX: 0000000000000a03 RSI: 0000000000000040 RDI: ffff888230078178
RBP: 0000000000000000 R08: 000000000000002c R09: ffffed1075c7df8e
R10: ffff8883ae3efc6b R11: ffffed1075c7df8d R12: 0000000000000000
R13: ffff88823869a2c8 R14: ffff8881012e0460 R15: dffffc0000000000
FS:  00007f350ac1f740(0000) GS:ffff8883ae200000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f350a6ed6a0 CR3: 0000000237456000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ? ext4_xattr_set_entry+0x3b7/0x2320
 ? ext4_xattr_block_set+0x0/0x2020
 ? ext4_xattr_set_entry+0x0/0x2320
 ? ext4_xattr_check_entries+0x77/0x310
 ? ext4_xattr_ibody_set+0x23b/0x340
 ext4_xattr_move_to_block+0x594/0x720
 ext4_expand_extra_isize_ea+0x59a/0x10f0
 __ext4_expand_extra_isize+0x278/0x3f0
 __ext4_mark_inode_dirty.cold+0x347/0x410
 ext4_rename+0xed3/0x174f
 vfs_rename+0x13a7/0x2510
 do_renameat2+0x55d/0x920
 __x64_sys_rename+0x7d/0xb0
 do_syscall_64+0x3b/0xa0
 entry_SYSCALL_64_after_hwframe+0x72/0xdc

As 'ext4_rename' will modify 'old.inode' ctime and mark inode dirty,
which may trigger expand 'extra_isize' and allocate block. If inode
didn't init quota will lead to warning.  To solve above issue, init
'old.inode' firstly in 'ext4_rename'.

Reported-by: syzbot+98346927678ac3059c77@syzkaller.appspotmail.com
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20221107015335.2524319-1-yebin@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  fs/ext4/xattr.c
  fs/ext4/namei.c

Diff excerpt:

Not included in this email. See the upstream URL for the full patch.

Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=67f6d5a4043f3db0c6bb0e14a0d97a7be8bfb8b5

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2022-50346 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2022-50346

The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.

The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.

The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.

Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:

  Conservative CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:H
  The Best / paranoid CVSS score: 5.3

The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.

CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.

A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.

  Conservative ActionableScore: 2
  Paranoid ActionableScore: 4

The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.

For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:

  ActionableScore below 5   -> MODERATE REGULAR
  ActionableScore 5 or more -> MODERATE 7.0

The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.

There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).

KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.

AL-KERNEL base severity for this report: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).

Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).