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.
CVSS Details
- CVSS 3.1 Base Score: 5.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade kernel6.18-debuginfo-common-x86_64Upgrade kernel6.18-modules-extra-commonUpgrade kernel6.12-libbpf-debuginfoUpgrade kernel6.18-tools-develUpgrade kernel6.12-tools-debuginfoUpgrade kernel6.12-libbpf-staticUpgrade kernel6.12-libbpfUpgrade kernel6.18-develUpgrade kernel6.12-develUpgrade kernel6.18Upgrade bpftool6.18Upgrade kernel6.12-headersUpgrade kernel-livepatch-6.18.25-52.107Upgrade perf6.18Upgrade python3-perf6.12-debuginfoUpgrade perf6.12-debuginfoUpgrade kernel6.18-toolsUpgrade bpftool6.12Upgrade perf6.18-debuginfoUpgrade kernel6.12Upgrade kernel6.12-debuginfo-common-x86_64Upgrade kernel6.12-tools-develUpgrade perf6.12Upgrade kernel6.18-modules-extraUpgrade kernel6.18-tools-debuginfoUpgrade python3-perf6.18Upgrade bpftool6.18-debuginfoUpgrade python3-perf6.18-debuginfoUpgrade kernel6.12-modules-extra-commonUpgrade kernel6.18-headersUpgrade bpftool6.12-debuginfoUpgrade kernel6.12-debuginfo-common-aarch64Upgrade kernel6.12-modules-extraUpgrade kernel6.12-libbpf-develUpgrade kernel6.18-debuginfo-common-aarch64Upgrade kernel6.12-toolsUpgrade kernel-livepatch-6.12.80-105.147Upgrade kernel6.12-debuginfoUpgrade python3-perf6.12Upgrade kernel6.18-debuginfo | May 6, 2026 | Apr 2, 2026 |
| Debian | — | Upgrade linux | Jul 23, 2026 | Jul 23, 2026 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Apr 2, 2026 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Jul 10, 2026 | Apr 2, 2026 |
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