[PATCH] drm/nouveau: avoid a use-after-free when BO init fails

[PATCH] drm/nouveau: avoid a use-after-free when BO init fails

[Jeremy Cline]

nouveau_bo_init() is backed by ttm_bo_init() and ferries its return code
back to the caller. On failures, ttm_bo_init() invokes the provided
destructor which should de-initialize and free the memory.

Thus, when nouveau_bo_init() returns an error the gem object has already
been released and the memory freed by nouveau_bo_del_ttm().

Fixes: 019cbd4a4feb ("drm/nouveau: Initialize GEM object before TTM object")
Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Jeremy Cline <jcline@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_gem.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
index 787d05eefd9c..d30157cc7169 100644
--- a/drivers/gpu/drm/nouveau/nouveau_gem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
@@ -211,10 +211,8 @@ nouveau_gem_new(struct nouveau_cli *cli, u64 size, int align, uint32_t domain,
 	}
 
 	ret = nouveau_bo_init(nvbo, size, align, domain, NULL, NULL);
-	if (ret) {
-		nouveau_bo_ref(NULL, &nvbo);
+	if (ret)
 		return ret;
-	}
 
 	/* we restrict allowed domains on nv50+ to only the types
 	 * that were requested at creation time.  not possibly on
-- 
2.28.0

Re: [PATCH] drm/nouveau: avoid a use-after-free when BO init fails

[Lyude Paul]

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

On Wed, 2020-12-02 at 19:02 -0500, Jeremy Cline wrote:
> nouveau_bo_init() is backed by ttm_bo_init() and ferries its return code
> back to the caller. On failures, ttm_bo_init() invokes the provided
> destructor which should de-initialize and free the memory.
> 
> Thus, when nouveau_bo_init() returns an error the gem object has already
> been released and the memory freed by nouveau_bo_del_ttm().
> 
> Fixes: 019cbd4a4feb ("drm/nouveau: Initialize GEM object before TTM object")
> Cc: Thierry Reding <treding@nvidia.com>
> Signed-off-by: Jeremy Cline <jcline@redhat.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_gem.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c
> b/drivers/gpu/drm/nouveau/nouveau_gem.c
> index 787d05eefd9c..d30157cc7169 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_gem.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
> @@ -211,10 +211,8 @@ nouveau_gem_new(struct nouveau_cli *cli, u64 size, int
> align, uint32_t domain,
>         }
>  
>         ret = nouveau_bo_init(nvbo, size, align, domain, NULL, NULL);
> -       if (ret) {
> -               nouveau_bo_ref(NULL, &nvbo);
> +       if (ret)
>                 return ret;
> -       }
>  
>         /* we restrict allowed domains on nv50+ to only the types
>          * that were requested at creation time.  not possibly on

-- 
Sincerely,
   Lyude Paul (she/her)
   Software Engineer at Red Hat
   
Note: I deal with a lot of emails and have a lot of bugs on my plate. If you've
asked me a question, are waiting for a review/merge on a patch, etc. and I
haven't responded in a while, please feel free to send me another email to check
on my status. I don't bite!

Re: [PATCH] drm/nouveau: avoid a use-after-free when BO init fails

[Karol Herbst]

Reviewed-by: Karol Herbst <kherbst@redhat.com>

and queued

On Fri, Mar 26, 2021 at 10:41 PM Lyude Paul <lyude@redhat.com> wrote:
>
> Reviewed-by: Lyude Paul <lyude@redhat.com>
>
> On Wed, 2020-12-02 at 19:02 -0500, Jeremy Cline wrote:
> > nouveau_bo_init() is backed by ttm_bo_init() and ferries its return code
> > back to the caller. On failures, ttm_bo_init() invokes the provided
> > destructor which should de-initialize and free the memory.
> >
> > Thus, when nouveau_bo_init() returns an error the gem object has already
> > been released and the memory freed by nouveau_bo_del_ttm().
> >
> > Fixes: 019cbd4a4feb ("drm/nouveau: Initialize GEM object before TTM object")
> > Cc: Thierry Reding <treding@nvidia.com>
> > Signed-off-by: Jeremy Cline <jcline@redhat.com>
> > ---
> >  drivers/gpu/drm/nouveau/nouveau_gem.c | 4 +---
> >  1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c
> > b/drivers/gpu/drm/nouveau/nouveau_gem.c
> > index 787d05eefd9c..d30157cc7169 100644
> > --- a/drivers/gpu/drm/nouveau/nouveau_gem.c
> > +++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
> > @@ -211,10 +211,8 @@ nouveau_gem_new(struct nouveau_cli *cli, u64 size, int
> > align, uint32_t domain,
> >         }
> >
> >         ret = nouveau_bo_init(nvbo, size, align, domain, NULL, NULL);
> > -       if (ret) {
> > -               nouveau_bo_ref(NULL, &nvbo);
> > +       if (ret)
> >                 return ret;
> > -       }
> >
> >         /* we restrict allowed domains on nv50+ to only the types
> >          * that were requested at creation time.  not possibly on
>
> --
> Sincerely,
>    Lyude Paul (she/her)
>    Software Engineer at Red Hat
>
> Note: I deal with a lot of emails and have a lot of bugs on my plate. If you've
> asked me a question, are waiting for a review/merge on a patch, etc. and I
> haven't responded in a while, please feel free to send me another email to check
> on my status. I don't bite!
>
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