CVE-2024-42161

/// Technical description

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.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References