Message-ID: <c1dbdc4a41e67496eb8533e5a271eb2bbdc318d6.camel@redhat.com>
Subject: Re: [PATCH] drm/nouveau/mmu: fix use-after-free bug in
 nvkm_vmm_pfn_map
From:   Lyude Paul <lyude@redhat.com>
To:     Zheng Wang <zyytlz.wz@163.com>, nouveau@lists.freedesktop.org
Cc:     bskeggs@redhat.com, kherbst@redhat.com, airlied@gmail.com,
        hackerzheng666@gmail.com, alex000young@gmail.com,
        security@kernel.org, daniel@ffwll.ch, Julia.Lawall@inria.fr,
        linux-kernel@vger.kernel.org
Date:   Mon, 06 Mar 2023 19:04:13 -0500
In-Reply-To: <20221029074654.203153-1-zyytlz.wz@163.com>
References: <20221029074654.203153-1-zyytlz.wz@163.com>
Organization: Red Hat Inc.
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Reviewed-by: Lyude Paul <lyude@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.
>=20
> Reported-by: Zheng Wang <hackerzheng666@gmail.com>
> Reported-by: Zhuorao Yang <alex000young@gmail.com>
>=20
> Fix it by returning to upper caller as soon as error occurs.
>=20
> Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
> ---
>  drivers/gpu/drm/nouveau/nvkm/subdev/mmu/vmm.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>=20
> 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, u6=
4 addr, u64 size, u64 *pfn)
>  						       page -
>  						       vmm->func->page, map);
>  			if (WARN_ON(!tmp)) {
> -				ret =3D -ENOMEM;
> -				goto next;
> +				return -ENOMEM;
>  			}
> =20
>  			if ((tmp->mapped =3D map))

--=20
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat