perf probe: Fix to free temporal Dwarf_Frame correctly

The commit 05c8d802fa52 ("perf probe: Fix to free temporal Dwarf_Frame")
tried to fix the memory leak of Dwarf_Frame, but it released the frame
at wrong point. Since the dwarf_frame_cfa(frame, &pf->fb_ops, &nops) can
return an address inside the frame data structure to pf->fb_ops, we can
not release the frame before using pf->fb_ops.

This reverts the commit and releases the frame afterwards (right before
returning from call_probe_finder) correctly.

Reported-and-Tested-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Reported-by: Michael Petlan <mpetlan@redhat.com>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: 05c8d802fa52 ("perf probe: Fix to free temporal Dwarf_Frame")
LPU-Reference: 20151125103432.1473.31009.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 1cab05a3831e65c25a3fa0e11650b4eb11a02b9a..2be10fb27172727fe15d5f3822ff194a5ad96d95 100644 (file)
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -654,6 +654,7 @@ static int convert_to_trace_point(Dwarf_Die *sp_die, Dwfl_Module *mod,
 static int call_probe_finder(Dwarf_Die *sc_die, struct probe_finder *pf)
 {
        Dwarf_Attribute fb_attr;
+       Dwarf_Frame *frame = NULL;
        size_t nops;
        int ret;
 
@@ -683,26 +684,24 @@ static int call_probe_finder(Dwarf_Die *sc_die, struct probe_finder *pf)
        ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops, &nops, 1);
        if (ret <= 0 || nops == 0) {
                pf->fb_ops = NULL;
-               ret = 0;
 #if _ELFUTILS_PREREQ(0, 142)
        } else if (nops == 1 && pf->fb_ops[0].atom == DW_OP_call_frame_cfa &&
                   pf->cfi != NULL) {
-               Dwarf_Frame *frame = NULL;
                if (dwarf_cfi_addrframe(pf->cfi, pf->addr, &frame) != 0 ||
                    dwarf_frame_cfa(frame, &pf->fb_ops, &nops) != 0) {
                        pr_warning("Failed to get call frame on 0x%jx\n",
                                   (uintmax_t)pf->addr);
-                       ret = -ENOENT;
+                       free(frame);
+                       return -ENOENT;
                }
-               free(frame);
 #endif
        }
 
        /* Call finder's callback handler */
-       if (ret >= 0)
-               ret = pf->callback(sc_die, pf);
+       ret = pf->callback(sc_die, pf);
 
-       /* *pf->fb_ops will be cached in libdw. Don't free it. */
+       /* Since *pf->fb_ops can be a part of frame. we should free it here. */
+       free(frame);
        pf->fb_ops = NULL;
 
        return ret;