Divide By Zero Affecting kernel-debuginfo package, versions <0:4.14.343-259.562.amzn2


Severity

Recommended
0.0
medium
0
10

Based on Amazon Linux security rating

    Threat Intelligence

    EPSS
    0.05% (19th percentile)

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  • Snyk ID SNYK-AMZN2-KERNELDEBUGINFO-7710781
  • published 20 Aug 2024
  • disclosed 3 Apr 2024

How to fix?

Upgrade Amazon-Linux:2 kernel-debuginfo to version 0:4.14.343-259.562.amzn2 or higher.
This issue was patched in ALAS2-2024-2549.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-debuginfo package and not the kernel-debuginfo package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2 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
Expand this section

Red Hat

5.5 medium
  • Attack Vector (AV)
    Local
  • Attack Complexity (AC)
    Low
  • Privileges Required (PR)
    Low
  • User Interaction (UI)
    None
  • Scope (S)
    Unchanged
  • Confidentiality (C)
    None
  • Integrity (I)
    None
  • Availability (A)
    High
Expand this section

SUSE

5.5 medium