Em Tue, Sep 15, 2020 at 11:59:13AM -0700, Ian Rogers escreveu: > On Tue, Sep 15, 2020 at 5:19 AM Arnaldo Carvalho de Melo > <a...@kernel.org> wrote: > > > > Em Tue, Sep 15, 2020 at 12:18:13PM +0900, Namhyung Kim escreveu: > > > The evsel->unit borrows a pointer of pmu event or alias instead of > > > owns a string. But tool event (duration_time) passes a result of > > > strdup() caused a leak. > > > > > > It was found by ASAN during metric test: > > > > Thanks, applied. > > Thanks Namhyung and Arnaldo, just to raise a meta point. A lot of the > parse-events asan failures were caused by a lack of strdup causing > frees of string literals. It seems we're now adding strdup defensively > but introducing memory leaks. Could we be doing this in a smarter way?
I hope so, the parsing code was always something I thought about auditing but never had time to work on, whatever you can do to help with that will be great! - Arnaldo > For C++ I'd likely use std::string and walk away. For perf code the > best source of "ownership" I've found is to look at the "delete" > functions and figure out ownership from what gets freed there - this > can be burdensome. For strings, the code is also using strbuf and > asprintf. One possible improvement could be to document ownership next > to the struct member variable declarations. Another idea would be to > declare a macro whose usage would look like: > > struct evsel { > ... > OWNER(char *name, "this"); > ... > UNOWNED(const char *unit); > ... > > Maybe then we could get a static analyzer to complain if a literal > were assigned to an owned struct variable. Perhaps if a strdup were > assigned to an UNOWNED struct variable perhaps it could warn too, as > presumably the memory allocation is a request to own the memory. > > There was a talk about GCC's -fanalyzer option doing malloc/free > checking at Linux plumbers 2 weeks ago: > https://linuxplumbersconf.org/event/7/contributions/721/attachments/542/961/2020-LPC-analyzer-talk.pdf > I added David Malcolm, the LPC presenter, as he may have ideas on how > we could do this in a better way. > > Thanks, > Ian > > > > > Direct leak of 210 byte(s) in 70 object(s) allocated from: > > > #0 0x7fe366fca0b5 in strdup > > > (/lib/x86_64-linux-gnu/libasan.so.5+0x920b5) > > > #1 0x559fbbcc6ea3 in add_event_tool util/parse-events.c:414 > > > #2 0x559fbbcc6ea3 in parse_events_add_tool util/parse-events.c:1414 > > > #3 0x559fbbd8474d in parse_events_parse util/parse-events.y:439 > > > #4 0x559fbbcc95da in parse_events__scanner util/parse-events.c:2096 > > > #5 0x559fbbcc95da in __parse_events util/parse-events.c:2141 > > > #6 0x559fbbc28555 in check_parse_id tests/pmu-events.c:406 > > > #7 0x559fbbc28555 in check_parse_id tests/pmu-events.c:393 > > > #8 0x559fbbc28555 in check_parse_cpu tests/pmu-events.c:415 > > > #9 0x559fbbc28555 in test_parsing tests/pmu-events.c:498 > > > #10 0x559fbbc0109b in run_test tests/builtin-test.c:410 > > > #11 0x559fbbc0109b in test_and_print tests/builtin-test.c:440 > > > #12 0x559fbbc03e69 in __cmd_test tests/builtin-test.c:695 > > > #13 0x559fbbc03e69 in cmd_test tests/builtin-test.c:807 > > > #14 0x559fbbc691f4 in run_builtin > > > /home/namhyung/project/linux/tools/perf/perf.c:312 > > > #15 0x559fbbb071a8 in handle_internal_command > > > /home/namhyung/project/linux/tools/perf/perf.c:364 > > > #16 0x559fbbb071a8 in run_argv > > > /home/namhyung/project/linux/tools/perf/perf.c:408 > > > #17 0x559fbbb071a8 in main > > > /home/namhyung/project/linux/tools/perf/perf.c:538 > > > #18 0x7fe366b68cc9 in __libc_start_main ../csu/libc-start.c:308 > > > > > > Acked-by: Jiri Olsa <jo...@redhat.com> > > > Fixes: f0fbb114e3025 ("perf stat: Implement duration_time as a proper > > > event") > > > Signed-off-by: Namhyung Kim <namhy...@kernel.org> > > > --- > > > tools/perf/util/parse-events.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/tools/perf/util/parse-events.c > > > b/tools/perf/util/parse-events.c > > > index b35e4bb1cecb..ece321ccf599 100644 > > > --- a/tools/perf/util/parse-events.c > > > +++ b/tools/perf/util/parse-events.c > > > @@ -416,7 +416,7 @@ static int add_event_tool(struct list_head *list, int > > > *idx, > > > return -ENOMEM; > > > evsel->tool_event = tool_event; > > > if (tool_event == PERF_TOOL_DURATION_TIME) > > > - evsel->unit = strdup("ns"); > > > + evsel->unit = "ns"; > > > return 0; > > > } > > > > > > -- > > > 2.28.0.618.gf4bc123cb7-goog > > > > > > > -- > > > > - Arnaldo -- - Arnaldo