[PATCH] drm/nouveau/mmu: Fix an UAF issue in NVKM

[Xinghui Li]

hi all
friendly ping...

<korantwork at gmail.com> 于2023年1月12日周四 15:18写道：
>
> From: Xinghui Li <korantli at tencent.com>
>
> In nvkm_mem_new_host, the mem is be alloced. And mem->memory is
> assigned to pmemory. During this process, the mem will be free if
> the error occurs. But the *pmemory still points to the &mem->memory
> which has been relased.Laterly, the nvkm_memory_unref will put the
> memory which points to the pmemory again.So, we set the *pmemory to
> NULL to avoid UAF issue.
>
> Reported-by: loydlv <loydlv at tencent.com>
> Signed-off-by: Xinghui Li <korantli at tencent.com>
> ---
>  drivers/gpu/drm/nouveau/nvkm/subdev/mmu/mem.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/mem.c b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/mem.c
> index 92e363dbbc5a..ab30eb1fc0a3 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/mem.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/mmu/mem.c
> @@ -185,6 +185,7 @@ nvkm_mem_new_host(struct nvkm_mmu *mmu, int type, u8 page, u64 size,
>         } else
>         if ( (ret = nvif_unvers(ret, &argv, &argc, args->vn))) {
>                 kfree(mem);
> +               *pmemory = NULL;
>                 return ret;
>         }
>
> --
> 2.31.1
>