Messages in this thread | | | Date | Wed, 10 Mar 2021 10:13:41 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH] perf synthetic events: Avoid write of uninitialized memory. |
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Em Wed, Mar 10, 2021 at 12:48:36PM +0100, Jiri Olsa escreveu: > On Tue, Mar 09, 2021 at 03:49:45PM -0800, Ian Rogers wrote: > > Account for alignment bytes in the zero-ing memset. > > > > Signed-off-by: Ian Rogers <irogers@google.com> > > --- > > tools/perf/util/synthetic-events.c | 9 +++++---- > > 1 file changed, 5 insertions(+), 4 deletions(-) > > > > diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c > > index b698046ec2db..31bf3dd6a1e0 100644 > > --- a/tools/perf/util/synthetic-events.c > > +++ b/tools/perf/util/synthetic-events.c > > @@ -424,7 +424,7 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, > > > > while (!io.eof) { > > static const char anonstr[] = "//anon"; > > - size_t size; > > + size_t size, aligned_size; > > > > /* ensure null termination since stack will be reused. */ > > event->mmap2.filename[0] = '\0'; > > @@ -484,11 +484,12 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, > > } > > > > size = strlen(event->mmap2.filename) + 1; > > - size = PERF_ALIGN(size, sizeof(u64)); > > + aligned_size = PERF_ALIGN(size, sizeof(u64)); > > event->mmap2.len -= event->mmap.start; > > event->mmap2.header.size = (sizeof(event->mmap2) - > > - (sizeof(event->mmap2.filename) - size)); > > - memset(event->mmap2.filename + size, 0, machine->id_hdr_size); > > + (sizeof(event->mmap2.filename) - aligned_size)); > > + memset(event->mmap2.filename + size, 0, machine->id_hdr_size + > > + (aligned_size - size)); > > so we did not zero the extra alignment bytes, nice ;-) looks good > > Acked-by: Jiri Olsa <jolsa@redhat.com>
That is really old:
Fixes: 1a853e36871b533c ("perf record: Allow specifying a pid to record")
Circa 2009, the PERF_RECORD_COMM is ok as TASK_COMM_LEN is 16.
But I think there are other places synthesizing PERF_RECORD_MMAP, jitdump maybe:
tools/perf/bench/inject-buildid.c, but it uses memset to zero the whole union, no problem.
tools/perf/util/jitdump.c jit_repipe_code_load() but it uses calloc to allocate the union perf_event, so no problem as well.
Thanks, applied.
- Arnaldo
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