# CVE-2023-53100: ext4: fix WARNING in ext4_update_inline_data

> A flaw in the Linux kernel ext4 filesystem allows a local attacker to trigger a kernel warning and potential denial of service via crafted inline data updates.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 2 May 2025
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2023-53100, DEBIAN-CVE-2023-53100, GHSA-mvqv-rc3q-g8hm, UBUNTU-CVE-2023-53100

## What is CVE-2023-53100?

CVE-2023-53100 is a high-severity denial of service vulnerability in Linux kernel, published on 2 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

ext4: fix WARNING in ext4_update_inline_data

Syzbot found the following issue:
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 without journal. Quota mode: none.
fscrypt: AES-256-CTS-CBC using implementation "cts-cbc-aes-aesni"
fscrypt: AES-256-XTS using implementation "xts-aes-aesni"
------------[ cut here ]------------
WARNING: CPU: 0 PID: 5071 at mm/page_alloc.c:5525 __alloc_pages+0x30a/0x560 mm/page_alloc.c:5525
Modules linked in:
CPU: 1 PID: 5071 Comm: syz-executor263 Not tainted 6.2.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
RIP: 0010:__alloc_pages+0x30a/0x560 mm/page_alloc.c:5525
RSP: 0018:ffffc90003c2f1c0 EFLAGS: 00010246
RAX: ffffc90003c2f220 RBX: 0000000000000014 RCX: 0000000000000000
RDX: 0000000000000028 RSI: 0000000000000000 RDI: ffffc90003c2f248
RBP: ffffc90003c2f2d8 R08: dffffc0000000000 R09: ffffc90003c2f220
R10: fffff52000785e49 R11: 1ffff92000785e44 R12: 0000000000040d40
R13: 1ffff92000785e40 R14: dffffc0000000000 R15: 1ffff92000785e3c
FS:  0000555556c0d300(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f95d5e04138 CR3: 00000000793aa000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __alloc_pages_node include/linux/gfp.h:237 [inline]
 alloc_pages_node include/linux/gfp.h:260 [inline]
 __kmalloc_large_node+0x95/0x1e0 mm/slab_common.c:1113
 __do_kmalloc_node mm/slab_common.c:956 [inline]
 __kmalloc+0xfe/0x190 mm/slab_common.c:981
 kmalloc include/linux/slab.h:584 [inline]
 kzalloc include/linux/slab.h:720 [inline]
 ext4_update_inline_data+0x236/0x6b0 fs/ext4/inline.c:346
 ext4_update_inline_dir fs/ext4/inline.c:1115 [inline]
 ext4_try_add_inline_entry+0x328/0x990 fs/ext4/inline.c:1307
 ext4_add_entry+0x5a4/0xeb0 fs/ext4/namei.c:2385
 ext4_add_nondir+0x96/0x260 fs/ext4/namei.c:2772
 ext4_create+0x36c/0x560 fs/ext4/namei.c:2817
 lookup_open fs/namei.c:3413 [inline]
 open_last_lookups fs/namei.c:3481 [inline]
 path_openat+0x12ac/0x2dd0 fs/namei.c:3711
 do_filp_open+0x264/0x4f0 fs/namei.c:3741
 do_sys_openat2+0x124/0x4e0 fs/open.c:1310
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_openat fs/open.c:1342 [inline]
 __se_sys_openat fs/open.c:1337 [inline]
 __x64_sys_openat+0x243/0x290 fs/open.c:1337
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Above issue happens as follows:
ext4_iget
   ext4_find_inline_data_nolock ->i_inline_off=164 i_inline_size=60
ext4_try_add_inline_entry
   __ext4_mark_inode_dirty
      ext4_expand_extra_isize_ea ->i_extra_isize=32 s_want_extra_isize=44
         ext4_xattr_shift_entries
	 ->after shift i_inline_off is incorrect, actually is change to 176
ext4_try_add_inline_entry
  ext4_update_inline_dir
    get_max_inline_xattr_value_size
      if (EXT4_I(inode)->i_inline_off)
	entry = (struct ext4_xattr_entry *)((void *)raw_inode +
			EXT4_I(inode)->i_inline_off);
        free += EXT4_XATTR_SIZE(le32_to_cpu(entry->e_value_size));
	->As entry is incorrect, then 'free' may be negative
   ext4_update_inline_data
      value = kzalloc(len, GFP_NOFS);
      -> len is unsigned int, maybe very large, then trigger warning when
         'kzalloc()'

To resolve the above issue we need to update 'i_inline_off' after
'ext4_xattr_shift_entries()'.  We do not need to set
EXT4_STATE_MAY_INLINE_DATA flag here, since ext4_mark_inode_dirty()
already sets this flag if needed.  Setting EXT4_STATE_MAY_INLINE_DATA
when it is needed may trigger a BUG_ON in ext4_writepages().

## Which versions are affected by CVE-2023-53100?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-53100?

Apply the vendor's patch.

## Is CVE-2023-53100 being exploited?

There is no known exploitation of CVE-2023-53100 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-53100 and fix it if it is affected.

What it is: CVE-2023-53100 is a high-severity denial of service vulnerability in Linux kernel, published on 2 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-53100 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-53100/ (Markdown: https://insights.sbomify.com/CVE-2023-53100/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53100
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53100
- OSV: https://osv.dev/vulnerability/CVE-2023-53100

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53100/
Summaries are generated and may contain mistakes; the official description above is the record.