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    Subject[PATCH v2 1/2] 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>
    ---
    Changes in v2:
    Remove 'td->next = 0x00' inside for loop.
    Remove unnecessary pointer nullification after free.
    Rename variable addr_aux to addr_next.

    drivers/usb/gadget/udc/amd5536udc.c | 17 ++++++++---------
    1 file changed, 8 insertions(+), 9 deletions(-)

    diff --git a/drivers/usb/gadget/udc/amd5536udc.c b/drivers/usb/gadget/udc/amd5536udc.c
    index ea03ca7..821d088 100644
    --- 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;
    --
    2.5.0
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