Messages in this thread Patch in this message | | | From | Eric Biggers <> | Subject | [PATCH] drm/vgem: fix use-after-free when drm_gem_handle_create() fails | Date | Tue, 26 Feb 2019 12:47:26 -0800 |
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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: 5ba6c9ff961a ("drm/vgem: Fix mmaping") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> --- drivers/gpu/drm/vgem/vgem_drv.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c index 5930facd6d2d8..70646d9da1596 100644 --- a/drivers/gpu/drm/vgem/vgem_drv.c +++ b/drivers/gpu/drm/vgem/vgem_drv.c @@ -189,15 +189,13 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev, return ERR_CAST(obj); 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
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