perf parse: Fix potential memory leak when handling tracepoint errors

An error may be in place when tracepoint_error is called, use
parse_events__handle_error to avoid a memory leak and to capture the
first and last error. Error detected by LLVM's libFuzzer using the
following event:

$ perf stat -e 'msr/event/,f:e'
event syntax error: 'msr/event/,f:e'
                     \___ can't access trace events

Error:  No permissions to read /sys/kernel/debug/tracing/events/f/e
Hint:   Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing/'

Initial error:
event syntax error: 'msr/event/,f:e'
                                \___ no value assigned for term
Run 'perf list' for a list of valid events

 Usage: perf stat [<options>] [<command>]

    -e, --event <event>   event selector. use 'perf list' to list available events

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: clang-built-linux@googlegroups.com
Link: http://lore.kernel.org/lkml/20191120180925.21787-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 6c313c4..ed7c008 100644 (file)
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -511,6 +511,7 @@ int parse_events_add_cache(struct list_head *list, int *idx,
 static void tracepoint_error(struct parse_events_error *e, int err,
                             const char *sys, const char *name)
 {
+       const char *str;
        char help[BUFSIZ];
 
        if (!e)
@@ -524,18 +525,18 @@ static void tracepoint_error(struct parse_events_error *e, int err,
 
        switch (err) {
        case EACCES:
-               e->str = strdup("can't access trace events");
+               str = "can't access trace events";
                break;
        case ENOENT:
-               e->str = strdup("unknown tracepoint");
+               str = "unknown tracepoint";
                break;
        default:
-               e->str = strdup("failed to add tracepoint");
+               str = "failed to add tracepoint";
                break;
        }
 
        tracing_path__strerror_open_tp(err, help, sizeof(help), sys, name);
-       e->help = strdup(help);
+       parse_events__handle_error(e, 0, strdup(str), strdup(help));
 }
 
 static int add_tracepoint(struct list_head *list, int *idx,