flash/nor/cfi: fix uninitialized write-mem pointer

In flash/nor/cfi.c:835 struct cfi_info is allocated by malloc(). As
write-mem was uninitialized the pointer pointed to an out of range
address, which led to a segmentation fault and crashed openocd.
This happened during flash-command of an external flash-bank, using
cfi.
Use calloc() instead.
While on it check for NULL return and remove unnecessary initialzation.

Change-Id: I0e2ffb90559afe7f090837023428dcc06b2e29f6
Signed-off-by: Mischa Studer <[email protected]>
Reviewed-on: http://openocd.zylin.com/6070
Tested-by: jenkins
Reviewed-by: Tomas Vanek <[email protected]>

Author: guitsy

src/flash/nor/cfi.c

@@ -832,17 +832,13 @@ int cfi_flash_bank_cmd(struct flash_bank *bank, unsigned int argc, const char **
 		return ERROR_FLASH_BANK_INVALID;
 	}
 
-	cfi_info = malloc(sizeof(struct cfi_flash_bank));
-	cfi_info->probed = false;
-	cfi_info->erase_region_info = NULL;
-	cfi_info->pri_ext = NULL;
+	cfi_info = calloc(1, sizeof(struct cfi_flash_bank));
+	if (cfi_info == NULL) {
+		LOG_ERROR("No memory for flash bank info");
+		return ERROR_FAIL;
+	}
 	bank->driver_priv = cfi_info;
 
-	cfi_info->x16_as_x8 = false;
-	cfi_info->jedec_probe = false;
-	cfi_info->not_cfi = false;
-	cfi_info->data_swap = false;
-
 	for (unsigned i = 6; i < argc; i++) {
 		if (strcmp(argv[i], "x16_as_x8") == 0)
 			cfi_info->x16_as_x8 = true;