Re: [PATCH 22/29] perf header: Validate bitmap size before allocating in do_read_bitmap()

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Mon, May 25, 2026 at 02:29:58AM +0000, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

> - [Low] The comment describing the per-node data layout does not accurately reflect the actual fields parsed by the code.

> > diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
 
> [ ... ]
 
> > @@ -3497,7 +3520,8 @@ static int process_mem_topology(struct feat_fd *ff,
> >  		return -1;
> >  	}

> > -	if (ff->size < 3 * sizeof(u64) + nr * 2 * sizeof(u64)) {
> > +	/* Per node: version(u64) + bitmap_size(u64) + bitmap data (>= 1 u64) */
 
> [Severity: Low]
> This isn't a bug, but does this comment accurately reflect the actual fields
> parsed by the code?
 
> It appears the first per-node field is actually the node ID, not the version,
> and this comment omits one of the two size fields written per node. It also
> assumes the bitmap data is always >= 1 u64 (when it could be 0). While the
> calculation nr * 3 * sizeof(u64) correctly accounts for the 3 metadata u64
> fields (node ID, size, and the second size from do_read_bitmap()), the text
> describing the layout seems slightly incorrect.

Addressed with:

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 351369ac4dc2c0a2..5b1fa1653d2a48cc 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -3532,7 +3532,7 @@ static int process_mem_topology(struct feat_fd *ff,
                return -1;
        }

-       /* Per node: version(u64) + bitmap_size(u64) + bitmap data (>= 1 u64) */
+       /* Per node: node_id(u64) + mem_size(u64) + bitmap_nr_bits(u64) */
        if (ff->size < 3 * sizeof(u64) + nr * 3 * sizeof(u64)) {
                pr_err("Invalid HEADER_MEM_TOPOLOGY: section too small (%zu) for %llu nodes\n",
                       ff->size, (unsigned long long)nr);
acme@x1:~/git/perf-tools-next$