Prevent uncleared memory leaking in rw_i93.cc

Bug: 139738828
Test: manual
Change-Id: I4e330d4ad1380dbd1e695f81b8183ca8b182b114
Exempt-From-Owner-Approval: new owner approved
(cherry picked from commit d8948d4a1fbb00abecc72227a1910d94633a84e8)

src/nfc/tags/rw_i93.cc

diff --git a/src/nfc/tags/rw_i93.cc b/src/nfc/tags/rw_i93.cc
index 495ee8f..132df3a 100644
--- a/src/nfc/tags/rw_i93.cc
+++ b/src/nfc/tags/rw_i93.cc
@@ -2656,12 +2656,20 @@
       }
 
       /* get buffer to store CC, zero length NDEF TLV and Terminator TLV */
-      p_i93->p_update_data = (uint8_t*)GKI_getbuf(RW_I93_FORMAT_DATA_LEN);
+      /* Block size could be either 4 or 8 or 16 or 32 bytes */
+      /* Get buffer for the largest block size I93_MAX_BLOCK_LENGH */
+      p_i93->p_update_data = (uint8_t*)GKI_getbuf(I93_MAX_BLOCK_LENGH);
 
       if (!p_i93->p_update_data) {
         LOG(ERROR) << StringPrintf("Cannot allocate buffer");
         rw_i93_handle_error(NFC_STATUS_FAILED);
         break;
+      } else if (p_i93->block_size > RW_I93_FORMAT_DATA_LEN) {
+        /* Possible leaking information from previous NFC transactions */
+        /* Clear previous values */
+        memset(p_i93->p_update_data, I93_ICODE_TLV_TYPE_NULL,
+               I93_MAX_BLOCK_LENGH);
+        android_errorWriteLog(0x534e4554, "139738828");
       }
 
       p = p_i93->p_update_data;