bionic: clear only the part of the buffer which is not overwritten afterward

Change-Id: I5ddd93f0557e5a7401460dc9fc8a55b330a79c3a
Signed-off-by: André Goddard Rosa <andre.goddard@gmail.com>
diff --git a/libc/bionic/malloc_leak.c b/libc/bionic/malloc_leak.c
index ad1d2b4..06f99fb 100644
--- a/libc/bionic/malloc_leak.c
+++ b/libc/bionic/malloc_leak.c
@@ -211,8 +211,7 @@
         size_t entrySize = (sizeof(size_t) * 2) + (sizeof(intptr_t) * entry->numEntries);
         if (entrySize < *infoSize) {
             /* we're writing less than a full entry, clear out the rest */
-            /* TODO: only clear out the part we're not overwriting? */
-            memset(head, 0, *infoSize);
+            memset(head + entrySize, 0, *infoSize - entrySize);
         } else {
             /* make sure the amount we're copying doesn't exceed the limit */
             entrySize = *infoSize;