RE: [PATCH] perf evlist: fix memory corruption for Kernel PMU event

[Song Bao Hua (Barry Song)]

> -----Original Message-----
> From: Andi Kleen [mailto:ak@xxxxxxxxxxxxxxx]
> Sent: Friday, October 2, 2020 12:07 PM
> To: Song Bao Hua (Barry Song) <song.bao.hua@xxxxxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx; Linuxarm <linuxarm@xxxxxxxxxx>; Peter
> Zijlstra <peterz@xxxxxxxxxxxxx>; Ingo Molnar <mingo@xxxxxxxxxx>; Arnaldo
> Carvalho de Melo <acme@xxxxxxxxxx>; Mark Rutland
> <mark.rutland@xxxxxxx>; Alexander Shishkin
> <alexander.shishkin@xxxxxxxxxxxxxxx>; Jiri Olsa <jolsa@xxxxxxxxxx>;
> Namhyung Kim <namhyung@xxxxxxxxxx>; Adrian Hunter
> <adrian.hunter@xxxxxxxxx>; Alexey Budankov
> <alexey.budankov@xxxxxxxxxxxxxxx>
> 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.

> 
> The problem seems to only happen on ARM64.

My platform which has this issue is really ARM64.

Thanks
Barry