xen/gntdev: don't dereference a null gntdev_dmabuf on allocation failure

Currently when the allocation of gntdev_dmabuf fails, the error exit
path will call dmabuf_imp_free_storage and causes a null pointer
dereference on gntdev_dmabuf.  Fix this by adding an error exit path
that won't free gntdev_dmabuf.

Detected by CoverityScan, CID#1472124 ("Dereference after null check")

Fixes: bf8dc55b1358 ("xen/gntdev: Implement dma-buf import functionality")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c
index faaa4d3970ea5d1731bbe8ac46c3f5add5994f83..589fd923c5508cb5dee94b2949aace2a9af21df6 100644 (file)
--- a/drivers/xen/gntdev-dmabuf.c
+++ b/drivers/xen/gntdev-dmabuf.c
@@ -569,7 +569,7 @@ static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
 
        gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
        if (!gntdev_dmabuf)
-               goto fail;
+               goto fail_no_free;
 
        gntdev_dmabuf->u.imp.refs = kcalloc(count,
                                            sizeof(gntdev_dmabuf->u.imp.refs[0]),
@@ -592,6 +592,7 @@ static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
 
 fail:
        dmabuf_imp_free_storage(gntdev_dmabuf);
+fail_no_free:
        return ERR_PTR(-ENOMEM);
 }