Merge branch 'Simplify bpf_snprintf verifier code'

Florent Revest says:

====================

Alexei requested a couple of cleanups to the bpf_snprintf and
ARG_PTR_TO_CONST_STR verifier code.

https://lore.kernel.org/bpf/CABRcYmL_SMT80UTyV98bRsOzW0wBd1sZcYUpTrcOAV+9m+YoWQ@mail.gmail.com/T/#t
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

kernel/bpf/verifier.c

@@ -5075,8 +5075,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 		u64 map_addr;
 		char *str_ptr;
 
-		if (reg->type != PTR_TO_MAP_VALUE || !map ||
-		    !bpf_map_is_rdonly(map)) {
+		if (!bpf_map_is_rdonly(map)) {
 			verbose(env, "R%d does not point to a readonly map'\n", regno);
 			return -EACCES;
 		}
@@ -5940,8 +5939,10 @@ static int check_bpf_snprintf_call(struct bpf_verifier_env *env,
 	fmt_map_off = fmt_reg->off + fmt_reg->var_off.value;
 	err = fmt_map->ops->map_direct_value_addr(fmt_map, &fmt_addr,
 						  fmt_map_off);
-	if (err)
-		return err;
+	if (err) {
+		verbose(env, "verifier bug\n");
+		return -EFAULT;
+	}
 	fmt = (char *)(long)fmt_addr + fmt_map_off;
 
 	/* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we