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SubjectRe: [PATCH] perf hists browser: Fix segfault if use symbol filter in cmdline


On 2015/12/2 23:49, Namhyung Kim wrote:
> Hi,
>
> On Wed, Dec 02, 2015 at 11:28:52AM +0000, Wang Nan wrote:
>> If feed perf a symbol filter in cmdline and the result is empty,
>> pressing 'Enter' in the hist browser causes crash:
>>
>> # ./perf report perf.data <-- Common mistake for beginners
>>
>> Then press 'Enter':
>>
>> perf: Segmentation fault
>> -------- backtrace --------
>> /home/wangnan/perf[0x53e578]
>> /lib64/libc.so.6(+0x3545f)[0x7f76bafe045f]
>> /home/wangnan/perf[0x539dd4]
>> /home/wangnan/perf(perf_evlist__tui_browse_hists+0x96)[0x53d216]
>> /home/wangnan/perf(cmd_report+0x1b9f)[0x442c7f]
>> /home/wangnan/perf[0x47efa2]
>> /home/wangnan/perf(main+0x5f5)[0x432fa5]
>> /lib64/libc.so.6(__libc_start_main+0xf4)[0x7f76bafccbd4]
>> /home/wangnan/perf[0x4330d4]
>>
>> This is because 'perf.data' is interperted as a symbol filter, and the
>> result is empty, so selection is empty. However,
>> hist_browser__toggle_fold() forgets to check it.
>>
>> This patch simply return faluse when selection is NULL.
> s/faluse/false/
>
>> Signed-off-by: Wang Nan <wangnan0@huawei.com>
>> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Acked-by: Namhyung Kim <namhyung@kernel.org>
>
> One nitpick below..
>
>> ---
>> tools/perf/ui/browsers/hists.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
>> index dcdcbaf..33da341 100644
>> --- a/tools/perf/ui/browsers/hists.c
>> +++ b/tools/perf/ui/browsers/hists.c
>> @@ -337,9 +337,12 @@ static bool hist_browser__toggle_fold(struct hist_browser *browser)
>> {
>> struct hist_entry *he = browser->he_selection;
>> struct map_symbol *ms = browser->selection;
>> - struct callchain_list *cl = container_of(ms, struct callchain_list, ms);
>> + struct callchain_list *cl = ms ? container_of(ms, struct callchain_list, ms) : NULL;
> I think this line is not needed as container_of doesn't make a pointer
> dereference by itself. Just checking below is enough IMHO.

I know it. Add it only for correctness.

Will be removed.

Thank you.

> Thanks,
> Namhyung
>
>
>> bool has_children;
>>
>> + if (!ms)
>> + return false;
>> +
>> if (ms == &he->ms)
>> has_children = hist_entry__toggle_fold(he);
>> else
>> --
>> 1.8.3.4
>>




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