Re: [PATCH v2] drm/vgem: fix use-after-free when drm_gem_handle_create() fails

[Rodrigo Siqueira]

On 02/26, Eric Biggers wrote:
> From: Eric Biggers 
> 
> If drm_gem_handle_create() fails in vgem_gem_create(), then the
> drm_vgem_gem_object is freed twice: once when the reference is dropped
> by drm_gem_object_put_unlocked(), and again by __vgem_gem_destroy().
> 
> This was hit by syzkaller using fault injection.
> 
> Fix it by skipping the second free.
> 
> Reported-by: syzbot+e73f2fb5ed5a5df36...@syzkaller.appspotmail.com
> Fixes: af33a9190d02 ("drm/vgem: Enable dmabuf import interfaces")
> Reviewed-by: Chris Wilson 
> Cc: Laura Abbott 
> Cc: Daniel Vetter 
> Cc: sta...@vger.kernel.org
> Signed-off-by: Eric Biggers 
> ---
>  drivers/gpu/drm/vgem/vgem_drv.c | 6 +-
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> index 5930facd6d2d8..11a8f99ba18c5 100644
> --- a/drivers/gpu/drm/vgem/vgem_drv.c
> +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> @@ -191,13 +191,9 @@ static struct drm_gem_object *vgem_gem_create(struct 
> drm_device *dev,
>   ret = drm_gem_handle_create(file, >base, handle);
>   drm_gem_object_put_unlocked(>base);
>   if (ret)
> - goto err;
> + return ERR_PTR(ret);
>  
>   return >base;
> -
> -err:
> - __vgem_gem_destroy(obj);
> - return ERR_PTR(ret);
>  }
>  
>  static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device 
> *dev,
> -- 
> 2.21.0.rc2.261.ga7da99ff1b-goog
> 
> ___
> dri-devel mailing list
> dri-de...@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

Applied to drm-misc-fixes.

Thanks

-- 
Rodrigo Siqueira
https://siqueira.tech
Graduate Student
Department of Computer Science
University of São Paulo


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Re: [PATCH v2] drm/vgem: fix use-after-free when drm_gem_handle_create() fails

[Laura Abbott]

On 2/26/19 1:44 PM, Eric Biggers wrote:

From: Eric Biggers 

If drm_gem_handle_create() fails in vgem_gem_create(), then the
drm_vgem_gem_object is freed twice: once when the reference is dropped
by drm_gem_object_put_unlocked(), and again by __vgem_gem_destroy().

This was hit by syzkaller using fault injection.

Fix it by skipping the second free.

Reported-by: syzbot+e73f2fb5ed5a5df36...@syzkaller.appspotmail.com
Fixes: af33a9190d02 ("drm/vgem: Enable dmabuf import interfaces")
Reviewed-by: Chris Wilson 
Cc: Laura Abbott 
Cc: Daniel Vetter 
Cc: sta...@vger.kernel.org
Signed-off-by: Eric Biggers 
---
  drivers/gpu/drm/vgem/vgem_drv.c | 6 +-
  1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 5930facd6d2d8..11a8f99ba18c5 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -191,13 +191,9 @@ static struct drm_gem_object *vgem_gem_create(struct 
drm_device *dev,
ret = drm_gem_handle_create(file, >base, handle);
drm_gem_object_put_unlocked(>base);
if (ret)
-   goto err;
+   return ERR_PTR(ret);
  
  	return >base;

-
-err:
-   __vgem_gem_destroy(obj);
-   return ERR_PTR(ret);
  }
  
  static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,





Acked-by: Laura Abbott 

[PATCH v2] drm/vgem: fix use-after-free when drm_gem_handle_create() fails

[Eric Biggers]

From: Eric Biggers 

If drm_gem_handle_create() fails in vgem_gem_create(), then the
drm_vgem_gem_object is freed twice: once when the reference is dropped
by drm_gem_object_put_unlocked(), and again by __vgem_gem_destroy().

This was hit by syzkaller using fault injection.

Fix it by skipping the second free.

Reported-by: syzbot+e73f2fb5ed5a5df36...@syzkaller.appspotmail.com
Fixes: af33a9190d02 ("drm/vgem: Enable dmabuf import interfaces")
Reviewed-by: Chris Wilson 
Cc: Laura Abbott 
Cc: Daniel Vetter 
Cc: sta...@vger.kernel.org
Signed-off-by: Eric Biggers 
---
 drivers/gpu/drm/vgem/vgem_drv.c | 6 +-
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 5930facd6d2d8..11a8f99ba18c5 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -191,13 +191,9 @@ static struct drm_gem_object *vgem_gem_create(struct 
drm_device *dev,
ret = drm_gem_handle_create(file, >base, handle);
drm_gem_object_put_unlocked(>base);
if (ret)
-   goto err;
+   return ERR_PTR(ret);
 
return >base;
-
-err:
-   __vgem_gem_destroy(obj);
-   return ERR_PTR(ret);
 }
 
 static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
-- 
2.21.0.rc2.261.ga7da99ff1b-goog