Re: [PATCH v8 6/6] perf c2c: print memory region data with stdio output

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Unsafe end address calculation for zero-length memory ranges, causing integer underflow.
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commit 353c7e26bf2f698e86dedab128c94a9970b19c51
Author: Thomas Falcon <thomas.falcon@intel.com>

perf c2c: print memory region data with stdio output

Print memory range data in perf-c2c subcommand. Only available in stdio
mode currently. If memory ranges are not supported or present, print
nothing.

> diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
> index e37c1a3a4ca5e..9d0182a7d4d5a 100644
> --- a/tools/perf/builtin-c2c.c
> +++ b/tools/perf/builtin-c2c.c
[ ... ]
> +	for (int i = 0; i < nr_ranges; i++) {
> +		struct memory_range *r = &env->memory_ranges[i];
> +
> +		fprintf(out, "Range %d: [0x%016" PRIx64 "-0x%016" PRIx64 "] Node %d, local region id %u, remote region id %u\n",
> +			i, r->base, r->base + r->length - 1, r->node,

[Severity: Low]
Does this code risk an integer underflow if a memory range has a length of 0?

If r->length is 0, the end address calculation underflows, which can lead to
an incorrect address being printed (for example, wrapping around to
0xffffffffffffffff if the base address is 0).

Since the parsing function process_memory_ranges() can allow 0-length
ranges, should this calculation check for r->length == 0 before
subtracting 1?

> +			r->local_region_id, r->remote_region_id);
> +	}
> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260910194324.98002-1-thomas.falcon@intel.com?part=6