# CVE-2022-49347: ext4: fix bug_on in ext4_writepages

> A bug in the Linux kernel ext4 filesystem causes a kernel panic when writing inline data and allocating blocks, leading to denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 26 Feb 2025
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2022-49347, GHSA-pqc9-xfp2-368x, UBUNTU-CVE-2022-49347

## What is CVE-2022-49347?

CVE-2022-49347 is a medium-severity denial of service vulnerability in Linux kernel, published on 26 Feb 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 bug_on in ext4_writepages

we got issue as follows:
EXT4-fs error (device loop0): ext4_mb_generate_buddy:1141: group 0, block bitmap and bg descriptor inconsistent: 25 vs 31513 free cls
------------[ cut here ]------------
kernel BUG at fs/ext4/inode.c:2708!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 2 PID: 2147 Comm: rep Not tainted 5.18.0-rc2-next-20220413+ #155
RIP: 0010:ext4_writepages+0x1977/0x1c10
RSP: 0018:ffff88811d3e7880 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88811c098000
RDX: 0000000000000000 RSI: ffff88811c098000 RDI: 0000000000000002
RBP: ffff888128140f50 R08: ffffffffb1ff6387 R09: 0000000000000000
R10: 0000000000000007 R11: ffffed10250281ea R12: 0000000000000001
R13: 00000000000000a4 R14: ffff88811d3e7bb8 R15: ffff888128141028
FS:  00007f443aed9740(0000) GS:ffff8883aef00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020007200 CR3: 000000011c2a4000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 do_writepages+0x130/0x3a0
 filemap_fdatawrite_wbc+0x83/0xa0
 filemap_flush+0xab/0xe0
 ext4_alloc_da_blocks+0x51/0x120
 __ext4_ioctl+0x1534/0x3210
 __x64_sys_ioctl+0x12c/0x170
 do_syscall_64+0x3b/0x90

It may happen as follows:
1. write inline_data inode
vfs_write
  new_sync_write
    ext4_file_write_iter
      ext4_buffered_write_iter
        generic_perform_write
          ext4_da_write_begin
            ext4_da_write_inline_data_begin -> If inline data size too
            small will allocate block to write, then mapping will has
            dirty page
                ext4_da_convert_inline_data_to_extent ->clear EXT4_STATE_MAY_INLINE_DATA
2. fallocate
do_vfs_ioctl
  ioctl_preallocate
    vfs_fallocate
      ext4_fallocate
        ext4_convert_inline_data
          ext4_convert_inline_data_nolock
            ext4_map_blocks -> fail will goto restore data
            ext4_restore_inline_data
              ext4_create_inline_data
              ext4_write_inline_data
              ext4_set_inode_state -> set inode EXT4_STATE_MAY_INLINE_DATA
3. writepages
__ext4_ioctl
  ext4_alloc_da_blocks
    filemap_flush
      filemap_fdatawrite_wbc
        do_writepages
          ext4_writepages
            if (ext4_has_inline_data(inode))
              BUG_ON(ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA))

The root cause of this issue is we destory inline data until call
ext4_writepages under delay allocation mode.  But there maybe already
convert from inline to extent.  To solve this issue, we call
filemap_flush first..

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2022-49347?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2022-49347?

Apply the vendor's patch.

## Is CVE-2022-49347 being exploited?

There is no known exploitation of CVE-2022-49347 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-2022-49347 and fix it if it is affected.

What it is: CVE-2022-49347 is a medium-severity denial of service vulnerability in Linux kernel, published on 26 Feb 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-2022-49347 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-2022-49347/ (Markdown: https://insights.sbomify.com/CVE-2022-49347/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-49347
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-49347
- OSV: https://osv.dev/vulnerability/CVE-2022-49347

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-49347/
Summaries are generated and may contain mistakes; the official description above is the record.