Re: [PATCH v4 02/10] perf tools: Try linked debug files for DSO debug info

[Namhyung Kim <namhyung@kernel.org>]

On Mon, Oct 12, 2026 at 11:56:52PM +0000, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] perf dso: DEBUGLINK path resolution flaws in dso__read_binary_type_filename
> --
> 
> commit 0c61bd07a4d26ed6f7bfc347b3ec0fe6ffc13ca0
> Author: Namhyung Kim <namhyung@kernel.org>
> 
> perf tools: Try linked debug files for DSO debug info
> 
> This commit modifies dso__find_dbginfo_type() to include
> DSO_BINARY_TYPE__DEBUGLINK in its search array. This allows perf to follow
> .gnu_debuglink to locate debug information in separate files.
> 
> > diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
> > index df03f84c97235..913877b84b2d4 100644
> > --- a/tools/perf/util/dso.c
> > +++ b/tools/perf/util/dso.c
> > @@ -2111,6 +2111,7 @@ void dso__find_dbginfo_type(struct dso *dso)
> >  		DSO_BINARY_TYPE__OPENEMBEDDED_DEBUGINFO,
> >  		DSO_BINARY_TYPE__BUILDID_DEBUGINFO,
> >  		DSO_BINARY_TYPE__SYSTEM_PATH_DSO,
> > +		DSO_BINARY_TYPE__DEBUGLINK,
> 
> [Severity: Medium]
> Enabling DSO_BINARY_TYPE__DEBUGLINK here exposes path resolution regressions in
> dso__read_binary_type_filename().
> 
> If the filename lacks slashes, does this logic create an empty string for
> dso_dir, breaking relative paths?
> 
> tools/perf/util/dso.c:dso__read_binary_type_filename() {
> 	...
> 	last_slash = filename + len;
> 	while (last_slash != filename && *last_slash != '/')
> 		last_slash--;
> 
> 	strncpy(dso_dir, filename, last_slash - filename);
> 	dso_dir[last_slash-filename] = '\0';
> 	...
> }

Then it'd be a separate, pre-existing issue.  Will handle it
independently.

> 
> Additionally, does this direct host filesystem I/O bypass the container mount
> namespace (/proc/<pid>/root/) fallback context?
> 
> tools/perf/util/dso.c:dso__read_binary_type_filename() {
> 	...
> 	if (!is_regular_file(filename)) {
> 		ret = -1;
> 		break;
> 	}
> 
> 	ret = filename__read_debuglink(filename, symfile, PATH_MAX);
> 	...
> }
> 
> Finally, does this inject the symfs-prefixed dso_dir into the middle of the
> /usr/lib/debug path, searching the host filesystem instead of the symfs
> chroot?

Also this is known, separate issue.  Let me handle it in a separate
series after this.

Thanks,
Namhyung

> 
> tools/perf/util/dso.c:dso__read_binary_type_filename() {
> 	...
> 	for (i = 0; i < ARRAY_SIZE(debuglink_paths); i++) {
> 		snprintf(filename, size,
> 				debuglink_paths[i], dso_dir, symfile);
> 	...
> }
> 
> >  		DSO_BINARY_TYPE__NOT_FOUND,
> >  	};
> >  	const enum dso_binary_type *type;
> 
> -- 
> Sashiko AI review · https://sashiko.dev/#/patchset/20261012234654.60666-1-namhyung@kernel.org?part=2