| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.19 098/134] drm/vkms: fix use-after-free when drm_gem_handle_create() fails | Date | Mon, 1 Apr 2019 19:02:14 +0200 |
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4.19-stable review patch. If anyone has any objections, please let me know.
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From: Eric Biggers <ebiggers@google.com>
commit 36b6c9ed45afe89045973e8dee1b004dd5372d40 upstream.
If drm_gem_handle_create() fails in vkms_gem_create(), then the vkms_gem_object is freed twice: once when the reference is dropped by drm_gem_object_put_unlocked(), and again by the extra calls to drm_gem_object_release() and kfree().
Fix it by skipping the second release and free.
This bug was originally found in the vgem driver by syzkaller using fault injection, but I noticed it's also present in the vkms driver.
Fixes: 559e50fd34d1 ("drm/vkms: Add dumb operations") Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com> Cc: Haneen Mohammed <hamohammed.sa@gmail.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com> Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190226220858.214438-1-ebiggers@kernel.org Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/gpu/drm/vkms/vkms_gem.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
--- a/drivers/gpu/drm/vkms/vkms_gem.c +++ b/drivers/gpu/drm/vkms/vkms_gem.c @@ -110,11 +110,8 @@ struct drm_gem_object *vkms_gem_create(s ret = drm_gem_handle_create(file, &obj->gem, handle); drm_gem_object_put_unlocked(&obj->gem); - if (ret) { - drm_gem_object_release(&obj->gem); - kfree(obj); + if (ret) return ERR_PTR(ret); - } return &obj->gem; }
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