Em Mon, Jun 17, 2019 at 05:11:40PM +0800, Leo Yan escreveu:
> trace__init_bpf_map_syscall_args() invokes trace__syscall_info() to
> retrieve system calls information, it always passes NULL for 'evsel'
> argument; when id is an invalid value then the logging will try to
> output event name, this triggers NULL pointer dereference.
>
> This patch directly uses string "unknown" for event name when 'evsel'
> is NULL pointer.
>
> Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
> ---
> tools/perf/builtin-trace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index 5cd74651db4c..49dfb2fd393b 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -1764,7 +1764,7 @@ static struct syscall *trace__syscall_info(struct trace *trace,
> static u64 n;
>
> pr_debug("Invalid syscall %d id, skipping (%s, %" PRIu64 ")\n",
> - id, perf_evsel__name(evsel), ++n);
> + id, evsel ? perf_evsel__name(evsel) : "unknown", ++n);
> return NULL;
What do you think of this instead?
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 68beef8f47ff..1d6af95b9207 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -590,6 +590,9 @@ const char *perf_evsel__name(struct perf_evsel *evsel)
{
char bf[128];
+ if (!evsel)
+ goto out_unknown;
+
if (evsel->name)
return evsel->name;
@@ -629,7 +632,10 @@ const char *perf_evsel__name(struct perf_evsel *evsel)
evsel->name = strdup(bf);
- return evsel->name ?: "unknown";
+ if (evsel->name)
+ return evsel->name;
+out_unknown:
+ return "unknown";
}
const char *perf_evsel__group_name(struct perf_evsel *evsel)
