From: Arnaldo Carvalho de Melo <acme@redhat.com>

Date: Mon, 2 Mar 2020 11:23:03 -0300

Subject: perf env: Do not return pointers to local variables

Git-commit: ebcb9464a2ae3a547e97de476575c82ece0e93e2

References: git-fixes

​

It is possible to return a pointer to a local variable when looking up

the architecture name for the running system and no normalization is

done on that value, i.e. we may end up returning the uts.machine local

variable.

​

While this doesn't happen on most arches, as normalization takes place,

lets fix this by making that a static variable and optimize it a bit by

not always running uname(), only the first time.

​

Noticed in fedora rawhide running with:

​

  [perfbuilder@a5ff49d6e6e4 ~]$ gcc --version

  gcc (GCC) 10.0.1 20200216 (Red Hat 10.0.1-0.8)

​

Reported-by: Jiri Olsa <jolsa@kernel.org>

Cc: Adrian Hunter <adrian.hunter@intel.com>

Cc: Namhyung Kim <namhyung@kernel.org>

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Acked-by: Tony Jones <tonyj@suse.de>

---

 tools/perf/util/env.c | 4 ++--

 1 file changed, 2 insertions(+), 2 deletions(-)

​

diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c

index 6242a9215df7..4154f944f474 100644

--- a/tools/perf/util/env.c

+++ b/tools/perf/util/env.c

@@ -343,11 +343,11 @@ static const char *normalize_arch(char *arch)

 const char *perf_env__arch(struct perf_env *env)

 {

-   struct utsname uts;

    char *arch_name;

    if (!env || !env->arch) { /* Assume local operation */

-       if (uname(&uts) < 0)

+       static struct utsname uts = { .machine[0] = '\0', };

+       if (uts.machine[0] == '\0' && uname(&uts) < 0)

            return NULL;

        arch_name = uts.machine;

    } else

​

​