Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix constant blinding for PROBE_MEM32 stores BPF_ST | BPF_PROBE_MEM32 immediate stores are not handled by bpf_jit_blind_insn(), allowing user-controlled 32-bit immediates to survive unblinded into JIT-compiled native code when bpf_jit_harden >= 1. The root cause is that convert_ctx_accesses() rewrites BPF_ST|BPF_MEM to BPF_ST|BPF_PROBE_MEM32 for arena pointer stores during verification, before bpf_jit_blind_constants() runs during JIT compilation. The blinding switch only matches BPF_ST|BPF_MEM (mode 0x60), not BPF_ST|BPF_PROBE_MEM32 (mode 0xa0). The instruction falls through unblinded. Add BPF_ST|BPF_PROBE_MEM32 cases to bpf_jit_blind_insn() alongside the existing BPF_ST|BPF_MEM cases. The blinding transformation is identical: load the blinded immediate into BPF_REG_AX via mov+xor, then convert the immediate store to a register store (BPF_STX). The rewritten STX instruction must preserve the BPF_PROBE_MEM32 mode so the architecture JIT emits the correct arena addressing (R12-based on x86-64). Cannot use the BPF_STX_MEM() macro here because it hardcodes BPF_MEM mode; construct the instruction directly instead.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 6082b6c328b5486da2b356eae94b8b83c98b5565 before 56af722756ed82fee2ae5d5b4d04743407506195; affected 6082b6c328b5486da2b356eae94b8b83c98b5565 before ccbf29b28b5554f9d65b2fb53b994673ad58b3bf; affected 6082b6c328b5486da2b356eae94b8b83c98b5565 before de641ea08f8fff6906e169d2576c2ac54e562fbb; affected 6082b6c328b5486da2b356eae94b8b83c98b5565 before 2321a9596d2260310267622e0ad8fbfa6f95378f |
| Linux / Linux | affected 6.9; unaffected 0 before 6.9; unaffected 6.12.80 through 6.12.*; unaffected 6.18.21 through 6.18.*; unaffected 6.19.11 through 6.19.*; unaffected 7.0 through * |
CWE
No CWE identifiers supplied.