Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 19 Jan 2023 22:15:00 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH] perf buildid: Avoid copy of uninitialized memory |
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Em Thu, Jan 19, 2023 at 08:57:21AM -0800, Ian Rogers escreveu: > On Thu, Jan 19, 2023 at 8:39 AM Arnaldo Carvalho de Melo > <acme@kernel.org> wrote: > > > > Em Thu, Jan 19, 2023 at 01:29:30PM -0300, Arnaldo Carvalho de Melo escreveu: > > > 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. > > > > Humm, don't we better do it as: > > > > + memcpy(&ev.build_id.build_id, pos->bid.data, min(pos->bid.size, sizeof(pos->bid.data)); > > > > Lemme check what is setting that pos->bid.size.... > > > > Things like sysfs__read_build_id() that does such checks, but perhaps we > > should be defensive and do it in this function as well? > > Defensive is good, another option would be an assert but they can be > compiled out. Do you want me to repost?
Please.
- Arnaldo
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