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Commit 2ea1c197 authored by Eric Biggers's avatar Eric Biggers Committed by Greg Kroah-Hartman
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drm/vgem: fix use-after-free when drm_gem_handle_create() fails 



commit 21d2b122732318b48c10b7262e15595ce54511d3 upstream.

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: default avatar <syzbot+e73f2fb5ed5a5df36d33@syzkaller.appspotmail.com>
Fixes: af33a919 ("drm/vgem: Enable dmabuf import interfaces")
Reviewed-by: default avatarChris 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: default avatarEric Biggers <ebiggers@google.com>
Acked-by: default avatarLaura Abbott <labbott@redhat.com>
Signed-off-by: default avatarRodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190226214451.195123-1-ebiggers@kernel.org


Signed-off-by: default avatarMaxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0d9ef3f5

drivers/gpu/drm/vgem/vgem_drv.c

+1 −5
Original line number Diff line number Diff line
@@ -192,13 +192,9 @@ 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,