xhci: check for failed dma pool allocation

Fail and free the container context in case dma_pool_alloc() can't allocate
the raw context data part of it

This patch should be backported to kernels as old as 2.6.31, that
contain the commit d115b048 "USB: xhci:
Support for 64-byte contexts".
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: John Youn <johnyoun@synopsys.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-mem.c

@@ -373,6 +373,10 @@ static struct xhci_container_ctx *xhci_alloc_container_ctx(struct xhci_hcd *xhci
 		ctx->size += CTX_SIZE(xhci->hcc_params);
 
 	ctx->bytes = dma_pool_alloc(xhci->device_pool, flags, &ctx->dma);
+	if (!ctx->bytes) {
+		kfree(ctx);
+		return NULL;
+	}
 	memset(ctx->bytes, 0, ctx->size);
 	return ctx;
 }