Messages in this thread Patch in this message | | | Date | Tue, 13 Feb 2018 10:45:51 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH] perf report: Fix a memory corrupton issue when enabling --branch-history |
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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
however we know the final count from callchain_cursor itself, the attached patch might do the same job, right?
also could we now get rid of iter->max_stack?
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;
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