Messages in this thread | | | From | Ian Rogers <> | Date | Wed, 8 Jul 2020 17:54:47 -0700 | Subject | Re: [PATCH v2] Fix annotate.c use of uninitialized value error |
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On Fri, Oct 25, 2019 at 3:11 PM Ian Rogers <irogers@google.com> wrote: > > It looks like this wasn't merged to tip. Does anything need addressing > to get it merged? > > Thanks, > Ian > > On Wed, Aug 7, 2019 at 4:32 AM Jiri Olsa <jolsa@redhat.com> wrote: > > > > On Mon, Jul 29, 2019 at 01:57:50PM -0700, Numfor Mbiziwo-Tiapo wrote: > > > Our local MSAN (Memory Sanitizer) build of perf throws a warning > > > that comes from the "dso__disassemble_filename" function in > > > "tools/perf/util/annotate.c" when running perf record. > > > > > > The warning stems from the call to readlink, in which "build_id_path" > > > was being read into "linkname". Since readlink does not null terminate, > > > an uninitialized memory access would later occur when "linkname" is > > > passed into the strstr function. This is simply fixed by null-terminating > > > "linkname" after the call to readlink. > > > > > > To reproduce this warning, build perf by running: > > > make -C tools/perf CLANG=1 CC=clang EXTRA_CFLAGS="-fsanitize=memory\ > > > -fsanitize-memory-track-origins" > > > > > > (Additionally, llvm might have to be installed and clang might have to > > > be specified as the compiler - export CC=/usr/bin/clang) > > > > > > then running: > > > tools/perf/perf record -o - ls / | tools/perf/perf --no-pager annotate\ > > > -i - --stdio > > > > > > Please see the cover letter for why false positive warnings may be > > > generated. > > > > > > Signed-off-by: Numfor Mbiziwo-Tiapo <nums@google.com> > > > > Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Arnaldo, I think this got overlooked. Thanks,
Ian
> > thanks, > > jirka > > > > > --- > > > tools/perf/util/annotate.c | 15 +++++++++++---- > > > 1 file changed, 11 insertions(+), 4 deletions(-) > > > > > > diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c > > > index 70de8f6b3aee..e1b075b52dce 100644 > > > --- a/tools/perf/util/annotate.c > > > +++ b/tools/perf/util/annotate.c > > > @@ -1627,6 +1627,7 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil > > > char *build_id_filename; > > > char *build_id_path = NULL; > > > char *pos; > > > + int len; > > > > > > if (dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS && > > > !dso__is_kcore(dso)) > > > @@ -1655,10 +1656,16 @@ static int dso__disassemble_filename(struct dso *dso, char *filename, size_t fil > > > if (pos && strlen(pos) < SBUILD_ID_SIZE - 2) > > > dirname(build_id_path); > > > > > > - if (dso__is_kcore(dso) || > > > - readlink(build_id_path, linkname, sizeof(linkname)) < 0 || > > > - strstr(linkname, DSO__NAME_KALLSYMS) || > > > - access(filename, R_OK)) { > > > + if (dso__is_kcore(dso)) > > > + goto fallback; > > > + > > > + len = readlink(build_id_path, linkname, sizeof(linkname) - 1); > > > + if (len < 0) > > > + goto fallback; > > > + > > > + linkname[len] = '\0'; > > > + if (strstr(linkname, DSO__NAME_KALLSYMS) || > > > + access(filename, R_OK)) { > > > fallback: > > > /* > > > * If we don't have build-ids or the build-id file isn't in the > > > -- > > > 2.22.0.709.g102302147b-goog > > >
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