usb: gadget: udc: avoid use of freed pointer

Rewrite udc_free_dma_chain() function to avoid use of pointer after free.

Addresses-Coverity-ID: 1091172
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

diff --git a/drivers/usb/gadget/udc/amd5536udc.c b/drivers/usb/gadget/udc/amd5536udc.c
index ea03ca7..821d088 100644 (file)
--- a/drivers/usb/gadget/udc/amd5536udc.c
+++ b/drivers/usb/gadget/udc/amd5536udc.c
@@ -611,21 +611,20 @@ udc_alloc_request(struct usb_ep *usbep, gfp_t gfp)
 static int udc_free_dma_chain(struct udc *dev, struct udc_request *req)
 {
        int ret_val = 0;
-       struct udc_data_dma     *td;
-       struct udc_data_dma     *td_last = NULL;
+       struct udc_data_dma *td = req->td_data;
        unsigned int i;
 
+       dma_addr_t addr_next = 0x00;
+       dma_addr_t addr = (dma_addr_t)td->next;
+
        DBG(dev, "free chain req = %p\n", req);
 
        /* do not free first desc., will be done by free for request */
-       td_last = req->td_data;
-       td = phys_to_virt(td_last->next);
-
        for (i = 1; i < req->chain_len; i++) {
-               pci_pool_free(dev->data_requests, td,
-                             (dma_addr_t)td_last->next);
-               td_last = td;
-               td = phys_to_virt(td_last->next);
+               td = phys_to_virt(addr);
+               addr_next = (dma_addr_t)td->next;
+               pci_pool_free(dev->data_requests, td, addr);
+               addr = addr_next;
        }
 
        return ret_val;