Use of Uninitialized Resource Affecting kernel-default-devel package, versions <5.14.21-150500.55.73.1


Severity

Recommended
high

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-SLES155-KERNELDEFAULTDEVEL-7706874
  • published17 Aug 2024
  • disclosed16 Aug 2024

Introduced: 16 Aug 2024

CVE-2024-42161  (opens in a new tab)
CWE-908  (opens in a new tab)

How to fix?

Upgrade SLES:15.5 kernel-default-devel to version 5.14.21-150500.55.73.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-default-devel package and not the kernel-default-devel package as distributed by SLES. See How to fix? for SLES:15.5 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