mmc: wbsd: implement check for dma mapping error

wbsd_request_dma() does not check for dma mapping errors.

Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/wbsd.c

@@ -1395,23 +1395,25 @@ static void wbsd_request_dma(struct wbsd_host *host, int dma)
 	 */
 	host->dma_addr = dma_map_single(mmc_dev(host->mmc), host->dma_buffer,
 		WBSD_DMA_SIZE, DMA_BIDIRECTIONAL);
+	if (dma_mapping_error(mmc_dev(host->mmc), host->dma_addr))
+		goto kfree;
 
 	/*
 	 * ISA DMA must be aligned on a 64k basis.
 	 */
 	if ((host->dma_addr & 0xffff) != 0)
-		goto kfree;
+		goto unmap;
 	/*
 	 * ISA cannot access memory above 16 MB.
 	 */
 	else if (host->dma_addr >= 0x1000000)
-		goto kfree;
+		goto unmap;
 
 	host->dma = dma;
 
 	return;
 
-kfree:
+unmap:
 	/*
 	 * If we've gotten here then there is some kind of alignment bug
 	 */
@@ -1421,6 +1423,7 @@ static void wbsd_request_dma(struct wbsd_host *host, int dma)
 		WBSD_DMA_SIZE, DMA_BIDIRECTIONAL);
 	host->dma_addr = 0;
 
+kfree:
 	kfree(host->dma_buffer);
 	host->dma_buffer = NULL;
 
@@ -1434,7 +1437,7 @@ static void wbsd_request_dma(struct wbsd_host *host, int dma)
 
 static void wbsd_release_dma(struct wbsd_host *host)
 {
-	if (host->dma_addr) {
+	if (!dma_mapping_error(mmc_dev(host->mmc), host->dma_addr)) {
 		dma_unmap_single(mmc_dev(host->mmc), host->dma_addr,
 			WBSD_DMA_SIZE, DMA_BIDIRECTIONAL);
 	}