CVE-2025-40079 riscv, bpf: Sign extend struct ops return values properly

In the Linux kernel, the following vulnerability has been resolved: riscv, bpf: Sign extend struct ops return values properly The nsbpfqdisc selftest triggers a kernel panic: Unable to handle kernel paging request at virtual address ffffffffa38dbf58 Current testprogs pgtable: 4K pagesize, 57-bit...