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).

Classification

CVE ID: CVE-2025-22048

Affected Products

Vendor: Linux

Product: Linux, Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.02% (probability of being exploited)

EPSS Percentile: 3.07% (scored less or equal to compared to others)

EPSS Date: 2025-04-20 (when was this score calculated)

References

https://nvd.nist.gov/vuln/detail/CVE-2025-22048
https://git.kernel.org/stable/c/7df2696256a034405d3c5a71b3a4c54725de4404
https://git.kernel.org/stable/c/223d565d8892481684091cfbaf3466f2b0e289d3
https://git.kernel.org/stable/c/780628a780b622759d9e5adc76d15432144da1a3
https://git.kernel.org/stable/c/996e90ab446641553e8e21707b38b9709605e0e0
https://git.kernel.org/stable/c/60f3caff1492e5b8616b9578c4bedb5c0a88ed14

Timeline