Do not allocate zero sized buffers - mac

Author: itayzafrir

components/TARGET_PSA/services/crypto/COMPONENT_SPE/psa_crypto_partition.c

@@ -255,34 +255,37 @@ static void psa_mac_operation(void)
                 }
 
                 case PSA_MAC_UPDATE: {
-
                     uint8_t *input_buffer = NULL;
                     size_t data_remaining = msg.in_size[1];
                     size_t allocation_size = MIN(data_remaining, MAX_DATA_CHUNK_SIZE_IN_BYTES);
                     size_t size_to_read = 0;
 
-                    input_buffer = mbedtls_calloc(1, allocation_size);
-                    if (input_buffer == NULL) {
-                        psa_mac_abort(msg.rhandle);
-                        status = PSA_ERROR_INSUFFICIENT_MEMORY;
-                    } else {
-                        while (data_remaining > 0) {
-                            size_to_read = MIN(data_remaining, MAX_DATA_CHUNK_SIZE_IN_BYTES);
-                            bytes_read = psa_read(msg.handle, 1, input_buffer, size_to_read);
-
-                            if (bytes_read != size_to_read) {
-                                SPM_PANIC("SPM read length mismatch");
+                    if (allocation_size > 0) {
+                        input_buffer = mbedtls_calloc(1, allocation_size);
+                        if (input_buffer == NULL) {
+                            psa_mac_abort(msg.rhandle);
+                            status = PSA_ERROR_INSUFFICIENT_MEMORY;
+                        } else {
+                            while (data_remaining > 0) {
+                                size_to_read = MIN(data_remaining, MAX_DATA_CHUNK_SIZE_IN_BYTES);
+
+                                bytes_read = psa_read(msg.handle, 1, input_buffer, size_to_read);
+                                if (bytes_read != size_to_read) {
+                                    SPM_PANIC("SPM read length mismatch");
+                                }
+
+                                status = psa_mac_update(msg.rhandle, input_buffer, bytes_read);
+                                // stop on error
+                                if (status != PSA_SUCCESS) {
+                                    break;
+                                }
+                                data_remaining = data_remaining - bytes_read;
                             }
 
-                            status = psa_mac_update(msg.rhandle, input_buffer, bytes_read);
-                            // stop on error
-                            if (status != PSA_SUCCESS) {
-                                break;
-                            }
-                            data_remaining = data_remaining - bytes_read;
+                            mbedtls_free(input_buffer);
                         }
-
-                        mbedtls_free(input_buffer);
+                    } else {
+                        status = psa_mac_update(msg.rhandle, input_buffer, allocation_size);
                     }
 
                     if (status != PSA_SUCCESS) {
@@ -293,25 +296,30 @@ static void psa_mac_operation(void)
                 }
 
                 case PSA_MAC_SIGN_FINISH: {
-                    size_t mac_size = 0;
-                    bytes_read = psa_read(msg.handle, 1, &mac_size,
-                                          msg.in_size[1]);
+                    uint8_t *mac = NULL;
+                    size_t mac_size = 0, mac_length = 0;
+
+                    bytes_read = psa_read(msg.handle, 1, &mac_size, msg.in_size[1]);
                     if (bytes_read != msg.in_size[1]) {
                         SPM_PANIC("SPM read length mismatch");
                     }
 
-                    size_t mac_length = 0;
-                    uint8_t *mac = mbedtls_calloc(1, mac_size);
-                    if (mac == NULL) {
-                        psa_mac_abort(msg.rhandle);
-                        status = PSA_ERROR_INSUFFICIENT_MEMORY;
-                    } else {
+                    if (mac_size > 0) {
+                        mac = mbedtls_calloc(1, mac_size);
+                        if (mac == NULL) {
+                            status = PSA_ERROR_INSUFFICIENT_MEMORY;
+                        }
+                    }
+
+                    if (status == PSA_SUCCESS) {
                         status = psa_mac_sign_finish(msg.rhandle, mac, mac_size, &mac_length);
                         if (status == PSA_SUCCESS) {
                             psa_write(msg.handle, 0, mac, mac_length);
                             psa_write(msg.handle, 1, &mac_length, sizeof(mac_length));
                         }
                         mbedtls_free(mac);
+                    } else {
+                        psa_mac_abort(msg.rhandle);
                     }
 
                     mbedtls_free(msg.rhandle);
@@ -320,26 +328,31 @@ static void psa_mac_operation(void)
                 }
 
                 case PSA_MAC_VERIFY_FINISH: {
+                    uint8_t *mac = NULL;
                     size_t mac_length = 0;
-                    bytes_read = psa_read(msg.handle, 1, &mac_length,
-                                          msg.in_size[1]);
-                    if (bytes_read != msg.in_size[1] ||
-                            mac_length != msg.in_size[2]) {
+
+                    bytes_read = psa_read(msg.handle, 1, &mac_length, msg.in_size[1]);
+                    if (bytes_read != msg.in_size[1] || mac_length != msg.in_size[2]) {
                         SPM_PANIC("SPM read length mismatch");
                     }
 
-                    uint8_t *mac = mbedtls_calloc(1, mac_length);
-                    if (mac == NULL) {
-                        psa_mac_abort(msg.rhandle);
-                        status = PSA_ERROR_INSUFFICIENT_MEMORY;
-                    } else {
-                        bytes_read = psa_read(msg.handle, 2, mac, msg.in_size[2]);
-                        if (bytes_read != msg.in_size[2]) {
-                            SPM_PANIC("SPM read length mismatch");
+                    if (mac_length > 0) {
+                        mac = mbedtls_calloc(1, mac_length);
+                        if (mac == NULL) {
+                            status = PSA_ERROR_INSUFFICIENT_MEMORY;
+                        } else {
+                            bytes_read = psa_read(msg.handle, 2, mac, mac_length);
+                            if (bytes_read != mac_length) {
+                                SPM_PANIC("SPM read length mismatch");
+                            }
                         }
+                    }
 
+                    if (status == PSA_SUCCESS) {
                         status = psa_mac_verify_finish(msg.rhandle, mac, mac_length);
                         mbedtls_free(mac);
+                    } else {
+                        psa_mac_abort(msg.rhandle);
                     }
 
                     mbedtls_free(msg.rhandle);