In the Linux kernel, the following vulnerability has been resolved: bpf: Reject programs with...

In the Linux kernel, the following vulnerability has been resolved:

bpf: Reject programs with inlined helpers if JIT is not available

When an architecture (such as LoongArch, ARM64, and RISC-V) implements bpf_jit_inlines_helper_call(), the verifier skips rewriting the helper call offset (insn->imm) in bpf_do_misc_fixups(). This is because the helper is expected to be inlined by the JIT compiler later. Therefore, insn->imm remains as the raw helper enum ID.

However, if JIT is disabled at runtime (net.core.bpf_jit_enable=0) or if JIT compilation fails dynamically (e.g., due to OOM), the program falls back to the BPF interpreter.

When the interpreter executes (__bpf_call_base + insn->imm) with the unpatched raw ID, it jumps into an invalid address space, triggering an instruction alignment fault or a kernel panic.

Although these helpers have valid C implementations in the kernel, the omission of offset rewriting makes runtime interpreter fallback fatal.

Fix this by setting 'prog->jit_required = 1' when helper call rewriting is skipped for JIT inlining. This ensures that such programs are safely rejected if JIT is not available, preventing the runtime kernel panic.