USB: whci-hcd: Fix potential memory leak in qset_add_urb_sg()

Do not leak memory by updating pointer with potentially
NULL realloc return value.

By the way remove unused local variable:
	struct whc_page_list_entry *entry;
More precisely, it was used to increment uninitialized value within one of cycles.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/whci/qset.c

@@ -436,7 +436,7 @@ static int qset_add_urb_sg(struct whc *whc, struct whc_qset *qset, struct urb *u
 	int i;
 	int ntds = 0;
 	struct whc_std *std = NULL;
-	struct whc_page_list_entry *entry;
+	struct whc_page_list_entry *new_pl_virt;
 	dma_addr_t prev_end = 0;
 	size_t pl_len;
 	int p = 0;
@@ -508,12 +508,15 @@ static int qset_add_urb_sg(struct whc *whc, struct whc_qset *qset, struct urb *u
 
 			pl_len = std->num_pointers * sizeof(struct whc_page_list_entry);
 
-			std->pl_virt = krealloc(std->pl_virt, pl_len, mem_flags);
-			if (std->pl_virt == NULL) {
+			new_pl_virt = krealloc(std->pl_virt, pl_len, mem_flags);
+			if (new_pl_virt == NULL) {
+				kfree(std->pl_virt);
+				std->pl_virt = NULL;
 				return -ENOMEM;
 			}
+			std->pl_virt = new_pl_virt;
 
-			for (;p < std->num_pointers; p++, entry++) {
+			for (;p < std->num_pointers; p++) {
 				std->pl_virt[p].buf_ptr = cpu_to_le64(dma_addr);
 				dma_addr = (dma_addr + WHCI_PAGE_SIZE) & ~(WHCI_PAGE_SIZE-1);
 			}