> -----Original Message-----
> From: Namhyung Kim [mailto:[email protected]]
> Sent: Tuesday, October 6, 2020 2:26 PM
> To: Song Bao Hua (Barry Song) <[email protected]>
> Cc: Andi Kleen <[email protected]>; [email protected]; Linuxarm
> <[email protected]>; Peter Zijlstra <[email protected]>; Ingo Molnar
> <[email protected]>; Arnaldo Carvalho de Melo <[email protected]>; Mark
> Rutland <[email protected]>; Alexander Shishkin
> <[email protected]>; Jiri Olsa <[email protected]>; Adrian
> Hunter <[email protected]>; Alexey Budankov
> <[email protected]>
> Subject: Re: [PATCH] perf evlist: fix memory corruption for Kernel PMU event
>
> Hello,
>
> On Fri, Oct 2, 2020 at 12:02 PM Song Bao Hua (Barry Song)
> <[email protected]> wrote:
> >
> >
> >
> > > -----Original Message-----
> > > From: Andi Kleen [mailto:[email protected]]
> > > Sent: Friday, October 2, 2020 12:07 PM
> > > To: Song Bao Hua (Barry Song) <[email protected]>
> > > Cc: [email protected]; Linuxarm <[email protected]>; Peter
> > > Zijlstra <[email protected]>; Ingo Molnar <[email protected]>;
> Arnaldo
> > > Carvalho de Melo <[email protected]>; Mark Rutland
> > > <[email protected]>; Alexander Shishkin
> > > <[email protected]>; Jiri Olsa <[email protected]>;
> > > Namhyung Kim <[email protected]>; Adrian Hunter
> > > <[email protected]>; Alexey Budankov
> > > <[email protected]>
> > > Subject: Re: [PATCH] perf evlist: fix memory corruption for Kernel PMU
> event
> > >
> > > On Fri, Oct 02, 2020 at 12:57:29AM +1300, Barry Song wrote:
> > > > Commit 7736627b865d ("perf stat: Use affinity for closing file
> > > > descriptors") will use FD(evsel, cpu, thread) to read and write file
> > > > descriptors xyarray. For a kernel PMU event, this leads to serious
> > > > memory corruption and perf crash.
> > > > I have seen evlist->core.cpus->nr is 1 while evsel has cpus->nr with
> > > > the total number of CPUs. so xyarray which is allocated by
> > > > evlist->core.cpus->nr will get overflow. This leads to various
> > > > segmentation faults in perf tool for kernel PMU events, eg:
> > > > ./perf stat -e bus_cycles sleep 1
> > > > *** Error in `./perf': free(): invalid next size (fast):
> > > > 0x00000000401e6370 *** Aborted (core dumped)
> > >
> > > Thanks.
> > >
> > > I believe there is already a patch queued for this.
> >
> > Andi, thanks! Could you share the link or the commit ID? I'd like to take a
> look at the fix.
> > I could still reproduce this issue in the latest linus' tree and I didn't
> > find any
> commit
> > related to this issue in linux-next and tip/perf/core.
>
> I think Andi was referring to this discussion which is not merged yet:
>
> https://lore.kernel.org/lkml/[email protected]
> m/
>
> I suggested a patch at the end. Can you please try it?
I tried the patch you suggested.
diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
index 2208444ecb44..cfcdbd7be066 100644
--- a/tools/lib/perf/evlist.c
+++ b/tools/lib/perf/evlist.c
@@ -45,6 +45,9 @@ static void __perf_evlist__propagate_maps(struct perf_evlist
*evlist,
if (!evsel->own_cpus || evlist->has_user_cpus) {
perf_cpu_map__put(evsel->cpus);
evsel->cpus = perf_cpu_map__get(evlist->cpus);
+ } else if (!evsel->system_wide && perf_cpu_map__empty(evlist->cpus)) {
+ perf_cpu_map__put(evsel->cpus);
+ evsel->cpus = perf_cpu_map__get(evlist->cpus);
} else if (evsel->cpus != evsel->own_cpus) {
perf_cpu_map__put(evsel->cpus);
evsel->cpus = perf_cpu_map__get(evsel->own_cpus);
it did fix the crash I have seen on arm64. I'd prefer you put the below fixes
tag in the commit log.
Fixes: 7736627b865d ("perf stat: Use affinity for closing file descriptors")
Perf stat began to crash from v5.4 kernel, so the fix should be backported to
stable trees.
Thanks
Barry
