perf probe: Fix a segfault if asked for variable it doesn't find

Fix a segfault bug by asking for variable it doesn't find.
Since the convert_variable() didn't handle error code returned
from convert_variable_location(), it just passed an incomplete
variable field and then a segfault was occurred when formatting
the field.

This fixes that bug by handling success code correctly in
convert_variable(). Other callers of convert_variable_location()
are correctly checking the return code.

This bug was introduced by following commit. But another hidden
erroneous error handling has been there previously (-ENOMEM case).

 commit 3d918a12a1b3088ac16ff37fa52760639d6e2403

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20140529105232.28251.30447.stgit@ltc230.yrl.intra.hitachi.co.jp
Signed-off-by: Jiri Olsa <jolsa@kernel.org>

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 5627621..9d8eb26 100644 (file)
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -511,12 +511,12 @@ static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
 
        ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
                                        &pf->sp_die, pf->tvar);
-       if (ret == -ENOENT)
+       if (ret == -ENOENT || ret == -EINVAL)
                pr_err("Failed to find the location of %s at this address.\n"
                       " Perhaps, it has been optimized out.\n", pf->pvar->var);
        else if (ret == -ENOTSUP)
                pr_err("Sorry, we don't support this variable location yet.\n");
-       else if (pf->pvar->field) {
+       else if (ret == 0 && pf->pvar->field) {
                ret = convert_variable_fields(vr_die, pf->pvar->var,
                                              pf->pvar->field, &pf->tvar->ref,
                                              &die_mem);