Use of Uninitialized Variable Affecting kernel-headers package, versions *


Severity

Recommended
0.0
medium
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-RHEL9-KERNELHEADERS-7587122
  • published5 Aug 2024
  • disclosed30 Jul 2024

Introduced: 30 Jul 2024

CVE-2024-42161  (opens in a new tab)
CWE-457  (opens in a new tab)
First added by Snyk

How to fix?

There is no fixed version for RHEL:9 kernel-headers.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-headers package and not the kernel-headers 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:

bpf: Avoid uninitialized value in BPF_CORE_READ_BITFIELD

[Changes from V1:

  • Use a default branch in the switch statement to initialize `val'.]

GCC warns that `val' may be used uninitialized in the BPF_CRE_READ_BITFIELD macro, defined in bpf_core_read.h as:

[...]
unsigned long long val;						      \
[...]								      \
switch (__CORE_RELO(s, field, BYTE_SIZE)) {			      \
case 1: val = *(const unsigned char *)p; break;			      \
case 2: val = *(const unsigned short *)p; break;		      \
case 4: val = *(const unsigned int *)p; break;			      \
case 8: val = *(const unsigned long long *)p; break;		      \
    }       							      \
[...]
val;								      \
}								      \

This patch adds a default entry in the switch statement that sets `val' to zero in order to avoid the warning, and random values to be used in case __builtin_preserve_field_info returns unexpected values for BPF_FIELD_BYTE_SIZE.

Tested in bpf-next master. No regressions.

CVSS Scores

version 3.1