Re: [bug report] perf env: Add perf_env__cpuid, perf_env__{nr_}pmu_mappings

[Jiri Olsa <olsajiri@gmail.com>]

On Tue, Feb 08, 2022 at 02:22:39PM +0300, Dan Carpenter wrote:
> Hello Kim Phillips,
> 
> This is a semi-automatic email about new static checker warnings.
> 
> The patch 9fe8895a27a8: "perf env: Add perf_env__cpuid,
> perf_env__{nr_}pmu_mappings" from Aug 17, 2021, leads to the
> following Smatch complaint:
> 
>     ./tools/perf/util/env.c:476 perf_env__nr_pmu_mappings()
>     error: we previously assumed 'env' could be null (see line 470)
> 
> ./tools/perf/util/env.c
>    469	
>    470		if (!env || !env->nr_pmu_mappings) { /* Assume local operation */
>                      ^^^
> Checks for NULL
> 
>    471			status = perf_env__read_pmu_mappings(env);
>    472			if (status)
>    473				return 0;
>    474		}
>    475	
>    476		return env->nr_pmu_mappings;
>                        ^^^^
> Unchecked dereference
> 
>    477	}
> 
> regards,
> dan carpenter

I think we need to bail out for !env

jirka


---
diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
index 579e44c59914..bc30d8cd2790 100644
--- a/tools/perf/util/env.c
+++ b/tools/perf/util/env.c
@@ -467,7 +467,10 @@ int perf_env__nr_pmu_mappings(struct perf_env *env)
 {
 	int status;
 
-	if (!env || !env->nr_pmu_mappings) { /* Assume local operation */
+	if (!env)
+		return 0;
+
+	if (!env->nr_pmu_mappings) { /* Assume local operation */
 		status = perf_env__read_pmu_mappings(env);
 		if (status)
 			return 0;
@@ -480,7 +483,10 @@ const char *perf_env__pmu_mappings(struct perf_env *env)
 {
 	int status;
 
-	if (!env || !env->pmu_mappings) { /* Assume local operation */
+	if (!env)
+		return NULL;
+
+	if (!env->pmu_mappings) { /* Assume local operation */
 		status = perf_env__read_pmu_mappings(env);
 		if (status)
 			return NULL;