udmabuf: fix a buf size overflow issue during udmabuf creation

by casting size_limit_mb to u64  when calculate pglimit.

Signed-off-by: Xiaogang Chen<[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Christian König <[email protected]>

Author: Xiaogang Chen

drivers/dma-buf/udmabuf.c

@@ -393,7 +393,7 @@ static long udmabuf_create(struct miscdevice *device,
 	if (!ubuf)
 		return -ENOMEM;
 
-	pglimit = (size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
+	pglimit = ((u64)size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
 	for (i = 0; i < head->count; i++) {
 		pgoff_t subpgcnt;