CVE-2024-56549: linux kernel Null Dereference — Fix

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.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.19 — 6.11.11
linux	linux_kernel	6.12 — 6.12.2

References

Advisories & Patches

https://git.kernel.org/stable/c/31ad74b20227ce6b40910ff78b1c604e42975cf1 https://git.kernel.org/stable/c/9582c7664103c9043e80a78f5c382aa6bdd67418 https://git.kernel.org/stable/c/f98770440c9bc468e2fd878212ec9526dbe08293

Other References

https://git.kernel.org/stable/c/785408bbafcfa24c9fc5b251f03fd0780ce182bd https://git.kernel.org/stable/c/d6bba3ece960129a553d4b16f1b00c884dc0993a https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html

Frequently Asked Questions

What is CVE-2024-56549? +

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. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2024-56549? +

CVE-2024-56549 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2024-56549? +

CVE-2024-56549 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2024-56549? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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