[PATCH v2] perf unwind: handle allocation failure in libdw__get_entries()

Check the return value of zalloc() before dereferencing the allocated
dwfl_ui_ti structure.

Return -ENOMEM when the allocation fails to avoid a NULL pointer
dereference.

Signed-off-by: Triet Hoang <[email protected]>
---
Changes in v2:
- Free the ui structure before returning -ENOMEM to avoid memory leak.
---
 tools/perf/util/unwind-libdw.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c
index 7f35042be567..fd8a5125468c 100644
--- a/tools/perf/util/unwind-libdw.c
+++ b/tools/perf/util/unwind-libdw.c
@@ -379,6 +379,11 @@ int libdw__get_entries(unwind_entry_cb_t cb, void *arg,
 		dwfl = dwfl_ui_ti->dwfl;
 	} else {
 		dwfl_ui_ti = zalloc(sizeof(*dwfl_ui_ti));
+		if (!dwfl_ui_ti) {
+			free(ui);
+			return -ENOMEM;
+		}
+
 		dwfl = dwfl_begin(&offline_callbacks);
 		if (!dwfl)
 			goto out;
-- 
2.53.0