perf tools: Fix segfault due to invalid kernel dso access

Jiri reported that the commit 96d78059d6d9 ("perf tools: Make vmlinux
short name more like kallsyms short name") segfaults on perf script.

When processing kernel mmap event, it should access the 'kernel'
variable as sometimes it cannot find a matching dso from build-id table
so 'dso' might be invalid.

Reported-by: Jiri Olsa <jolsa@redhat.com>
Tested-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1416285028-30572-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index d97309c87bd643f87c0a95efee4231c7af17ac28..b75b487574c753a6b713e494ec657ba65a45b83f 100644 (file)
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1106,8 +1106,8 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
                if (__machine__create_kernel_maps(machine, kernel) < 0)
                        goto out_problem;
 
-               if (strstr(dso->long_name, "vmlinux"))
-                       dso__set_short_name(dso, "[kernel.vmlinux]", false);
+               if (strstr(kernel->long_name, "vmlinux"))
+                       dso__set_short_name(kernel, "[kernel.vmlinux]", false);
 
                machine__set_kernel_mmap_len(machine, event);