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

[Andi Kleen]

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.

The problem seems to only happen on ARM64.

-Andi