[Nouveau] [PATCH] drm/nouveau/mmu: fix use-after-free bug in nvkm_vmm_pfn_map

[Lyude Paul]

Reviewed-by: Lyude Paul <lyude at redhat.com>

Will push upstream in a moment

On Sat, 2022-10-29 at 15:46 +0800, Zheng Wang wrote:
> If it failed in kzalloc, vma will be freed in nvkm_vmm_node_merge.
> The later use of vma will casue use after free.
> 
> Reported-by: Zheng Wang <hackerzheng666 at gmail.com>
> Reported-by: Zhuorao Yang <alex000young at gmail.com>
> 
> Fix it by returning to upper caller as soon as error occurs.
> 
> Signed-off-by: Zheng Wang <zyytlz.wz at 163.com>
> ---
>  drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> index ae793f400ba1..04befd28f80b 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c
> @@ -1272,8 +1272,7 @@ nvkm_vmm_pfn_map(struct nvkm_vmm *vmm, u8 shift, u64 addr, u64 size, u64 *pfn)
>  						       page -
>  						       vmm->func->page, map);
>  			if (WARN_ON(!tmp)) {
> -				ret = -ENOMEM;
> -				goto next;
> +				return -ENOMEM;
>  			}
>  
>  			if ((tmp->mapped = map))

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat