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Date: Thu, 19 Jan 2023 13:29:30 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ian Rogers <irogers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Tom Rix <trix@redhat.com>, Adrian Hunter <adrian.hunter@intel.com>,
	Leo Yan <leo.yan@linaro.org>, linux-perf-users@vger.kernel.org,
	linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
	Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH] perf buildid: Avoid copy of uninitialized memory
Message-ID: <Y8lv6oclCytPk7hN@kernel.org>
References: <20230113185732.134861-1-irogers@google.com>
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Em Thu, Jan 19, 2023 at 08:08:13AM -0800, Ian Rogers escreveu:
> On Fri, Jan 13, 2023 at 10:57 AM Ian Rogers <irogers@google.com> wrote:
> >
> > build_id__init only copies the buildid data up to size leaving the
> > rest of the data array uninitialized. Copying the full array during
> > synthesis means the written event contains uninitialized memory.  This
> > was detected by the Clang/LLVM memory sanitizer.
> >
> > Signed-off-by: Ian Rogers <irogers@google.com>
> > ---
> >  tools/perf/util/synthetic-events.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c
> > index 3ab6a92b1a6d..348d05e4ec03 100644
> > --- a/tools/perf/util/synthetic-events.c
> > +++ b/tools/perf/util/synthetic-events.c
> > @@ -2219,7 +2219,7 @@ int perf_event__synthesize_build_id(struct perf_tool *tool, struct dso *pos, u16
> >
> >         len = pos->long_name_len + 1;
> >         len = PERF_ALIGN(len, NAME_ALIGN);
> > -       memcpy(&ev.build_id.build_id, pos->bid.data, sizeof(pos->bid.data));
> > +       memcpy(&ev.build_id.build_id, pos->bid.data, pos->bid.size);
> 
> Ping. Should be an uncontroversial change to fix a copy of
> uninitialized memory into the perf.data file during synthesis.

Indeed, applied.

- Arnaldo