Fix potential memory leak when copying into existing SHA contexts and zero-initialize temp GetHash contexts

Author: night1rider

wolfcrypt/src/sha.c

@@ -1137,7 +1137,7 @@ int wc_ShaGetHash(wc_Sha* sha, byte* hash)
         return BAD_FUNC_ARG;
     }
 
-    WC_ALLOC_VAR_EX(tmpSha, wc_Sha, 1, NULL, DYNAMIC_TYPE_TMP_BUFFER,
+    WC_CALLOC_VAR_EX(tmpSha, wc_Sha, 1, NULL, DYNAMIC_TYPE_TMP_BUFFER,
         return MEMORY_E);
 
     ret = wc_ShaCopy(sha, tmpSha);

wolfcrypt/src/sha256.c

@@ -2546,7 +2546,7 @@ int wc_Sha224_Grow(wc_Sha224* sha224, const byte* in, int inSz)
             return BAD_FUNC_ARG;
         }
 
-        WC_ALLOC_VAR_EX(tmpSha224, wc_Sha224, 1, NULL,
+        WC_CALLOC_VAR_EX(tmpSha224, wc_Sha224, 1, NULL,
             DYNAMIC_TYPE_TMP_BUFFER, return MEMORY_E);
 
         ret = wc_Sha224Copy(sha224, tmpSha224);
@@ -2582,6 +2582,15 @@ int wc_Sha224_Grow(wc_Sha224* sha224, const byte* in, int inSz)
         ret = 0; /* Reset ret to 0 to avoid returning the callback error code */
 #endif /* WOLF_CRYPTO_CB && WOLF_CRYPTO_CB_COPY */
 
+        /* Free dst's msg buffer before copy to prevent potential memory leak
+         * when XMEMCPY overwrites dst with src's pointers. */
+    #if defined(WOLFSSL_HASH_KEEP)
+        if (dst->msg != NULL) {
+            XFREE(dst->msg, dst->heap, DYNAMIC_TYPE_TMP_BUFFER);
+            dst->msg = NULL;
+        }
+    #endif
+
         XMEMCPY(dst, src, sizeof(wc_Sha224));
 
     #ifdef WOLFSSL_SMALL_STACK_CACHE
@@ -2691,7 +2700,7 @@ int wc_Sha256GetHash(wc_Sha256* sha256, byte* hash)
         return BAD_FUNC_ARG;
     }
 
-    WC_ALLOC_VAR_EX(tmpSha256, wc_Sha256, 1, NULL, DYNAMIC_TYPE_TMP_BUFFER,
+    WC_CALLOC_VAR_EX(tmpSha256, wc_Sha256, 1, NULL, DYNAMIC_TYPE_TMP_BUFFER,
         return MEMORY_E);
 
     ret = wc_Sha256Copy(sha256, tmpSha256);
@@ -2728,6 +2737,15 @@ int wc_Sha256Copy(wc_Sha256* src, wc_Sha256* dst)
     ret = 0; /* Reset ret to 0 to avoid returning the callback error code */
 #endif /* WOLF_CRYPTO_CB && WOLF_CRYPTO_CB_COPY */
 
+    /* Free dst's msg buffer before copy to prevent potential memory leak
+     * when XMEMCPY overwrites dst with src's pointers. */
+#if defined(WOLFSSL_HASH_KEEP)
+    if (dst->msg != NULL) {
+        XFREE(dst->msg, dst->heap, DYNAMIC_TYPE_TMP_BUFFER);
+        dst->msg = NULL;
+    }
+#endif
+
     XMEMCPY(dst, src, sizeof(wc_Sha256));
 
 #ifdef WOLFSSL_MAXQ10XX_CRYPTO

wolfcrypt/src/sha512.c

@@ -2206,7 +2206,7 @@ static int Sha512_Family_GetHash(wc_Sha512* sha512, byte* hash,
         return BAD_FUNC_ARG;
     }
 
-    WC_ALLOC_VAR_EX(tmpSha512, wc_Sha512, 1, NULL, DYNAMIC_TYPE_TMP_BUFFER,
+    WC_CALLOC_VAR_EX(tmpSha512, wc_Sha512, 1, NULL, DYNAMIC_TYPE_TMP_BUFFER,
         return MEMORY_E);
 
     /* copy this sha512 into tmpSha */
@@ -2249,6 +2249,15 @@ int wc_Sha512Copy(wc_Sha512* src, wc_Sha512* dst)
     ret = 0; /* Reset ret to 0 to avoid returning the callback error code */
 #endif /* WOLF_CRYPTO_CB && WOLF_CRYPTO_CB_COPY */
 
+    /* Free dst's msg buffer before copy to prevent potential memory leak
+     * when XMEMCPY overwrites dst with src's pointers. */
+#if defined(WOLFSSL_HASH_KEEP)
+    if (dst->msg != NULL) {
+        XFREE(dst->msg, dst->heap, DYNAMIC_TYPE_TMP_BUFFER);
+        dst->msg = NULL;
+    }
+#endif
+
     XMEMCPY(dst, src, sizeof(wc_Sha512));
 #ifdef WOLFSSL_SMALL_STACK_CACHE
     /* This allocation combines the customary W buffer used by
@@ -2649,7 +2658,7 @@ int wc_Sha384GetHash(wc_Sha384* sha384, byte* hash)
         return BAD_FUNC_ARG;
     }
 
-    WC_ALLOC_VAR_EX(tmpSha384, wc_Sha384, 1, NULL, DYNAMIC_TYPE_TMP_BUFFER,
+    WC_CALLOC_VAR_EX(tmpSha384, wc_Sha384, 1, NULL, DYNAMIC_TYPE_TMP_BUFFER,
         return MEMORY_E);
 
     /* copy this sha384 into tmpSha */
@@ -2687,6 +2696,15 @@ int wc_Sha384Copy(wc_Sha384* src, wc_Sha384* dst)
     ret = 0; /* Reset ret to 0 to avoid returning the callback error code */
 #endif /* WOLF_CRYPTO_CB && WOLF_CRYPTO_CB_COPY */
 
+    /* Free dst's msg buffer before copy to prevent potential memory leak
+     * when XMEMCPY overwrites dst with src's pointers. */
+#if defined(WOLFSSL_HASH_KEEP)
+    if (dst->msg != NULL) {
+        XFREE(dst->msg, dst->heap, DYNAMIC_TYPE_TMP_BUFFER);
+        dst->msg = NULL;
+    }
+#endif
+
     XMEMCPY(dst, src, sizeof(wc_Sha384));
 
 #ifdef WOLFSSL_SMALL_STACK_CACHE