xen/grants: prevent integer overflow in gnttab_dma_alloc_pages()

The change from kcalloc() to kvmalloc() means that arg->nr_pages
might now be large enough that the "args->nr_pages << PAGE_SHIFT" can
result in an integer overflow.

Fixes: b3f7931f5c61 ("xen/gntdev: switch from kcalloc() to kvcalloc()")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/YxDROJqu/RPvR0bi@kili
Signed-off-by: Juergen Gross <jgross@suse.com>

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 738029d..e1ec725 100644 (file)
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -1047,6 +1047,9 @@ int gnttab_dma_alloc_pages(struct gnttab_dma_alloc_args *args)
        size_t size;
        int i, ret;
 
+       if (args->nr_pages < 0 || args->nr_pages > (INT_MAX >> PAGE_SHIFT))
+               return -ENOMEM;
+
        size = args->nr_pages << PAGE_SHIFT;
        if (args->coherent)
                args->vaddr = dma_alloc_coherent(args->dev, size,