[PATCH] perf tools: Fix segfault due to invalid kernel dso access

From: Namhyung Kim
Date: Mon Nov 17 2014 - 23:30:43 EST

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@xxxxxxxxxx>
Tested-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
tools/perf/util/machine.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 52e94902afb1..85033d80fd6a 100644
--- 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);


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