[PATCH 2/2] nouveau/dmem: Fix memory leak in `migrate_to_ram` upon copy error

[Yonatan Maman]

A copy push command might fail, causing `migrate_to_ram` to return a
dirty HIGH_USER page to the user.

This exposes a security vulnerability in the nouveau driver. To prevent
memory leaks in `migrate_to_ram` upon a copy error, allocate a zero
page for the destination page.

Signed-off-by: Yonatan Maman <yma...@nvidia.com>
Signed-off-by: Gal Shalom <galsha...@nvidia.com>
---
 drivers/gpu/drm/nouveau/nouveau_dmem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c 
b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index 6fb65b01d778..097bd3af0719 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -193,7 +193,7 @@ static vm_fault_t nouveau_dmem_migrate_to_ram(struct 
vm_fault *vmf)
        if (!spage || !(src & MIGRATE_PFN_MIGRATE))
                goto done;
 
-       dpage = alloc_page_vma(GFP_HIGHUSER, vmf->vma, vmf->address);
+       dpage = alloc_page_vma(GFP_HIGHUSER | __GFP_ZERO, vmf->vma, 
vmf->address);
        if (!dpage)
                goto done;
 
-- 
2.34.1