CVE-2025-22048: LoongArch: BPF: Don't override subprog's return value

Vulnerability summary

CVE-2025-22048 is a high (CVSS 7.8) vulnerability in linux. EPSS estimates a 0.21% chance of exploitation in the next 30 days, higher than 11.9% of scored vulnerabilities.

Timeline

1. 16-04-2025
   PublishedVulnerability first disclosed.
2. 30-10-2026
   Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: LoongArch: BPF: Don't override subprog's return value The verifier test `calls: div by 0 in subprog` triggers a panic at the ld.bu instruction. The ld.bu insn is trying to load byte from memory address returned by the subprog. The subprog actually set the correct address at the a5 register (dedicated register for BPF return values). But at commit 73c359d1d356 ("LoongArch: BPF: Sign-extend return values") we also sign extended a5 to the a0 register (return value in LoongArch). For function call insn, we later propagate the a0 register back to a5 register. This is right for native calls but wrong for bpf2bpf calls which expect zero-extended return value in a5 register. So only move a0 to a5 for native calls (i.e. non-BPF_PSEUDO_CALL).

No weakness data has been published for this record.