Re: [PATCH 5/5] perf arm-spe: Reject zero nr_cpu in metadata to prevent division by zero

[Namhyung Kim]

On Mon, Aug 03, 2026 at 04:02:22PM -0300, Arnaldo Carvalho de Melo wrote:
> On Mon, Aug 03, 2026 at 09:46:49PM +0300, Adrian Hunter wrote:
> > On 27/07/2026 19:17, Arnaldo Carvalho de Melo wrote:
> > > From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> > > 
> > > arm_spe__alloc_metadata() reads nr_cpu from the auxtrace_info priv
> > > array without validation.  When a crafted perf.data provides nr_cpu=0,
> > > the per_cpu_sz calculation divides by zero:
> > > 
> > >   per_cpu_sz = (metadata_size - (hdr_sz * sizeof(u64))) / (*nr_cpu);
> > > 
> > > Reject nr_cpu <= 0 early, before the division.  The caller already
> > > treats NULL return with metadata_ver != 1 as a parse failure.
> > > 
> > > Fixes: e52abceb4b6c2723 ("perf arm-spe: Dump metadata with version 2")
> > 
> > git blame shows 7842a4b6ff698 "perf arm-spe: Support metadata version 2"
> > for the relevant lines
> 
> That is right, Namhyung, can you please fix this Fixme tag while merging?

Sure, will do!

Thanks,
Namhyung