Divide By Zero Affecting kernel-64k-debug package, versions <0:5.14.0-284.73.1.el9_2


Severity

Recommended
high

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.05% (19th percentile)

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  • Snyk IDSNYK-RHEL9-KERNEL64KDEBUG-7448956
  • published15 Jul 2024
  • disclosed3 Apr 2024

Introduced: 3 Apr 2024

CVE-2024-26720  (opens in a new tab)
CWE-369  (opens in a new tab)

How to fix?

Upgrade RHEL:9 kernel-64k-debug to version 0:5.14.0-284.73.1.el9_2 or higher.
This issue was patched in RHSA-2024:4533.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-64k-debug package and not the kernel-64k-debug package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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

mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again

(struct dirty_throttle_control *)->thresh is an unsigned long, but is passed as the u32 divisor argument to div_u64(). On architectures where unsigned long is 64 bytes, the argument will be implicitly truncated.

Use div64_u64() instead of div_u64() so that the value used in the "is this a safe division" check is the same as the divisor.

Also, remove redundant cast of the numerator to u64, as that should happen implicitly.

This would be difficult to exploit in memcg domain, given the ratio-based arithmetic domain_drity_limits() uses, but is much easier in global writeback domain with a BDI_CAP_STRICTLIMIT-backing device, using e.g. vm.dirty_bytes=(1<<32)*PAGE_SIZE so that dtc->thresh == (1<<32)

CVSS Scores

version 3.1