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. Tested in bpf-next master. No regressions.

Severity MEDIUM

CVSS Score 6.3

CVSS Vector CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:H/A:H

CWE CWE-908

Public Exploit ✅ No

Source NVD

Published 2024-07-30

Updated 2026-06-02

Modified 2025-11-03

Fix URL https://git.kernel.org/stable/c/009367099eb61a4fc2af44d4eb06b6b4de7de6db

Software	From version	Fixed in
linux-kernel	6.7	6.9.9