tracing/probes: Fix to add NULL check for BTF APIs

Since find_btf_func_param() abd btf_type_by_id() can return NULL,
the caller must check the return value correctly.

Link: https://lore.kernel.org/all/169024903951.395371.11361556840733470934.stgit@devnote2/
Fixes: b576e09701c7 ("tracing/probes: Support function parameters if BTF is available")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index b2b726bea1f9e67f39d477509745a5b2a8bc667a..c68a727078525ce7d867ae4e6eb2097a74eaf869 100644 (file)
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -386,12 +386,12 @@ static const struct btf_type *find_btf_func_proto(const char *funcname)
 
        /* Get BTF_KIND_FUNC type */
        t = btf_type_by_id(btf, id);
-       if (!btf_type_is_func(t))
+       if (!t || !btf_type_is_func(t))
                return ERR_PTR(-ENOENT);
 
        /* The type of BTF_KIND_FUNC is BTF_KIND_FUNC_PROTO */
        t = btf_type_by_id(btf, t->type);
-       if (!btf_type_is_func_proto(t))
+       if (!t || !btf_type_is_func_proto(t))
                return ERR_PTR(-ENOENT);
 
        return t;
@@ -443,7 +443,7 @@ static int parse_btf_arg(const char *varname, struct fetch_insn *code,
        if (!ctx->params) {
                params = find_btf_func_param(ctx->funcname, &ctx->nr_params,
                                             ctx->flags & TPARG_FL_TPOINT);
-               if (IS_ERR(params)) {
+               if (IS_ERR_OR_NULL(params)) {
                        trace_probe_log_err(ctx->offset, NO_BTF_ENTRY);
                        return PTR_ERR(params);
                }
@@ -1273,7 +1273,7 @@ const char **traceprobe_expand_meta_args(int argc, const char *argv[],
 
        params = find_btf_func_param(ctx->funcname, &nr_params,
                                     ctx->flags & TPARG_FL_TPOINT);
-       if (IS_ERR(params)) {
+       if (IS_ERR_OR_NULL(params)) {
                if (args_idx != -1) {
                        /* $arg* requires BTF info */
                        trace_probe_log_err(0, NOSUP_BTFARG);