Zero out temporary arrays before use in PDF encryption.

BUG=387834
R=palmer@chromium.org

Review URL: https://codereview.chromium.org/386663003

core/src/fpdfapi/fpdf_parser/fpdf_parser_encrypt.cpp

diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_encrypt.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_encrypt.cpp
index e09bbbb..417801b 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_encrypt.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_encrypt.cpp
@@ -406,6 +406,7 @@
             copy_len = ukey.GetLength();
         }
         FXSYS_memset32(test, 0, sizeof(test));
+        FXSYS_memset32(tmpkey, 0, sizeof(tmpkey));
         FXSYS_memcpy32(test, (FX_LPCSTR)ukey, copy_len);
         for (int i = 19; i >= 0; i --) {
             for (int j = 0; j < key_len; j ++) {
@@ -466,6 +467,7 @@
     } else {
         for (int i = 19; i >= 0; i --) {
             FX_BYTE tempkey[32];
+            FXSYS_memset32(tempkey, 0, sizeof(tempkey));
             for (int j = 0; j < m_KeyLen; j ++) {
                 tempkey[j] = enckey[j] ^ i;
             }