Messages in this thread | | | Subject | Re: [PATCH] perf report: Fix a memory corrupton issue when enabling --branch-history | From | "Jin, Yao" <> | Date | Fri, 16 Feb 2018 10:25:31 +0800 |
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On 2/13/2018 10:00 PM, Jin, Yao wrote: > > > On 2/13/2018 5:45 PM, Jiri Olsa wrote: >> On Tue, Feb 13, 2018 at 04:44:28PM +0800, Jin Yao wrote: >>> Following command lines will cause perf crash. >>> >>> perf record -j call -g -a <application> >>> perf report --branch-history >>> >>> *** Error in `perf': double free or corruption (!prev): >>> 0x00000000104aa040 *** >>> ======= Backtrace: ========= >>> /lib/x86_64-linux-gnu/libc.so.6(+0x77725)[0x7f6b37254725] >>> /lib/x86_64-linux-gnu/libc.so.6(+0x7ff4a)[0x7f6b3725cf4a] >>> /lib/x86_64-linux-gnu/libc.so.6(cfree+0x4c)[0x7f6b37260abc] >>> perf[0x51b914] >>> perf(hist_entry_iter__add+0x1e5)[0x51f305] >>> perf[0x43cf01] >>> perf[0x4fa3bf] >>> perf[0x4fa923] >>> perf[0x4fd396] >>> perf[0x4f9614] >>> perf(perf_session__process_events+0x89e)[0x4fc38e] >>> perf(cmd_report+0x15d2)[0x43f202] >>> perf[0x4a059f] >>> perf(main+0x631)[0x427b71] >>> /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0)[0x7f6b371fd830] >>> perf(_start+0x29)[0x427d89] >>> >>> The memory corruption happens at: >>> >>> iter_add_next_cumulative_entry() >>> { >>> ... >>> for (i = 0; i < iter->curr; i++) { >>> ... >>> } >>> >>> Whatever in iter_next_cumulative_entry() or in >>> iter_add_next_cumulative_entry(), >>> they all don't check if iter->curr exceeds the array 'he_cache[]'. >>> >>> If there are too many nodes in callchain, it's possible that >>> iter->curr > >>> iter->max_stack, then memory corruption occurs. >>> >>> This patch will reallocate array 'he_cache[]' in >>> iter_next_cumulative_entry() >>> if necessary (the case of too many nodes in callchain). >> >> right, the max_stack does not say how many nodes end up in >> callchain_cursor at the end.. good catch, please mention >> that also in the changelog >> > > max_stack looks only to limit the number of calls but not for other > branches. > >> however we know the final count from callchain_cursor itself, >> the attached patch might do the same job, right? >> > > I think the attached patch is ok. > >> also could we now get rid of iter->max_stack? >> > > From my opinion, the option '--max-stack' in perf report looks not very > necessary. While it's just my personal opinion, need to hear from more > people. :) > > Thanks > Jin Yao > >> thanks, >> jirka >> >> >> --- >> diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c >> index b6140950301e..b50b7b70dcca 100644 >> --- a/tools/perf/util/hist.c >> +++ b/tools/perf/util/hist.c >> @@ -879,7 +879,7 @@ iter_prepare_cumulative_entry(struct >> hist_entry_iter *iter, >> * cumulated only one time to prevent entries more than 100% >> * overhead. >> */ >> - he_cache = malloc(sizeof(*he_cache) * (iter->max_stack + 1)); >> + he_cache = malloc(sizeof(*he_cache) * (callchain_cursor.nr + 1)); >> if (he_cache == NULL) >> return -ENOMEM; >>
Hi Jiri,
I guess you will post this patch, right?
Thanks Jin Yao
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