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[PATCH 2/2 RESEND] drm/vc4: Fix OOPSes from trying to cache a partially constructed BO.

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  [PATCH 2/2 RESEND] drm/vc4: Fix OOPSes from trying to cache a partially constructed BO. Eric Anholt <eric@anholt.net> - 2017-03-01 20:00 +0100
    Re: [PATCH 2/2 RESEND] drm/vc4: Fix OOPSes from trying to cache a  partially constructed BO. Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-03-02 10:00 +0100

#1590567 — [PATCH 2/2 RESEND] drm/vc4: Fix OOPSes from trying to cache a partially constructed BO.

If a CMA allocation failed, the partially constructed BO would be
unreferenced through the normal path, and we might choose to put it in
the BO cache.  If we then reused it before it expired from the cache,
the kernel would OOPS.

Signed-off-by: Eric Anholt <eric@anholt.net>
Fixes: c826a6e10644 ("drm/vc4: Add a BO cache.")
---
 drivers/gpu/drm/vc4/vc4_bo.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
index e5c7aa935b4b..af29432a6471 100644
--- a/drivers/gpu/drm/vc4/vc4_bo.c
+++ b/drivers/gpu/drm/vc4/vc4_bo.c
@@ -317,6 +317,14 @@ void vc4_free_object(struct drm_gem_object *gem_bo)
 		goto out;
 	}
 
+	/* If this object was partially constructed but CMA allocation
+	 * had failed, just free it.
+	 */
+	if (!bo->base.vaddr) {
+		vc4_bo_destroy(bo);
+		goto out;
+	}
+
 	cache_list = vc4_get_cache_list_for_size(dev, gem_bo->size);
 	if (!cache_list) {
 		vc4_bo_destroy(bo);
-- 
2.11.0

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#1590931 — Re: [PATCH 2/2 RESEND] drm/vc4: Fix OOPSes from trying to cache a partially constructed BO.

On Wed,  1 Mar 2017 10:56:02 -0800
Eric Anholt <eric@anholt.net> wrote:

> If a CMA allocation failed, the partially constructed BO would be
> unreferenced through the normal path, and we might choose to put it in
> the BO cache.  If we then reused it before it expired from the cache,
> the kernel would OOPS.
> 
> Signed-off-by: Eric Anholt <eric@anholt.net>
> Fixes: c826a6e10644 ("drm/vc4: Add a BO cache.")

Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>

> ---
>  drivers/gpu/drm/vc4/vc4_bo.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
> index e5c7aa935b4b..af29432a6471 100644
> --- a/drivers/gpu/drm/vc4/vc4_bo.c
> +++ b/drivers/gpu/drm/vc4/vc4_bo.c
> @@ -317,6 +317,14 @@ void vc4_free_object(struct drm_gem_object *gem_bo)
>  		goto out;
>  	}
>  
> +	/* If this object was partially constructed but CMA allocation
> +	 * had failed, just free it.
> +	 */
> +	if (!bo->base.vaddr) {
> +		vc4_bo_destroy(bo);
> +		goto out;
> +	}
> +
>  	cache_list = vc4_get_cache_list_for_size(dev, gem_bo->size);
>  	if (!cache_list) {
>  		vc4_bo_destroy(bo);

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