[PATCH bpf-next v2 2/3] bpf: Disallow interpreter fallback for gotox insn

[Leon Hwang]

The interpreter does not recognize the BPF_JMP|BPF_JA|BPF_X insn, which
is used for insn_array map. Thereafter, it would hit the BUG_ON() in
___bpf_prog_run() at run time.

[    2.563726] BPF interpreter: unknown opcode 0d (imm: 0x0)
[    2.564557] ------------[ cut here ]------------
[    2.565206] kernel BUG at kernel/bpf/core.c:2349!
[    2.565882] Oops: invalid opcode: 0000 [#1] SMP PTI

Set jit_required as true when insn_array map is used in the prog in
order to disallow interpreter fallback for gotox insn in
core.c::__bpf_prog_select_runtime().

Fixes: 493d9e0d6083 ("bpf, x86: add support for indirect jumps")
Signed-off-by: Leon Hwang <leon.hw...@linux.dev>
---
 kernel/bpf/verifier.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 3849d3d00e15..e2ef7836b7b5 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -17927,6 +17927,7 @@ static int __add_used_map(struct bpf_verifier_env *env, 
struct bpf_map *map)
                        return err;
                }
                env->insn_array_maps[env->insn_array_map_cnt++] = map;
+               env->prog->jit_required = true;
        }
 
        return env->used_map_cnt - 1;
-- 
2.55.0