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

Submitted by Eric Biggers on Feb. 26, 2019, 9:44 p.m.

Details

Message ID 20190226214451.195123-1-ebiggers@kernel.org
State Accepted
Commit 21d2b122732318b48c10b7262e15595ce54511d3
Headers show
Series "drm/vgem: fix use-after-free when drm_gem_handle_create() fails" ( rev: 2 ) in DRI devel

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Commit Message

Eric Biggers Feb. 26, 2019, 9:44 p.m.
From: Eric Biggers <ebiggers@google.com>

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+e73f2fb5ed5a5df36d33@syzkaller.appspotmail.com
Fixes: af33a9190d02 ("drm/vgem: Enable dmabuf import interfaces")
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 drivers/gpu/drm/vgem/vgem_drv.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

Patch hide | download patch | download mbox

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, &obj->base, handle);
 	drm_gem_object_put_unlocked(&obj->base);
 	if (ret)
-		goto err;
+		return ERR_PTR(ret);
 
 	return &obj->base;
-
-err:
-	__vgem_gem_destroy(obj);
-	return ERR_PTR(ret);
 }
 
 static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,

Comments

On 2/26/19 1:44 PM, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> 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+e73f2fb5ed5a5df36d33@syzkaller.appspotmail.com
> Fixes: af33a9190d02 ("drm/vgem: Enable dmabuf import interfaces")
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Laura Abbott <labbott@redhat.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: stable@vger.kernel.org
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
>   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, &obj->base, handle);
>   	drm_gem_object_put_unlocked(&obj->base);
>   	if (ret)
> -		goto err;
> +		return ERR_PTR(ret);
>   
>   	return &obj->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 <labbott@redhat.com>
On 02/26, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> 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+e73f2fb5ed5a5df36d33@syzkaller.appspotmail.com
> Fixes: af33a9190d02 ("drm/vgem: Enable dmabuf import interfaces")
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Laura Abbott <labbott@redhat.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: stable@vger.kernel.org
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
>  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, &obj->base, handle);
>  	drm_gem_object_put_unlocked(&obj->base);
>  	if (ret)
> -		goto err;
> +		return ERR_PTR(ret);
>  
>  	return &obj->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-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

Applied to drm-misc-fixes.

Thanks