This is a note to let you know that I've just added the patch titled
drm/virtio: Fix GEM handle creation UAF
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-virtio-fix-gem-handle-creation-uaf.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 52531258318ed59a2dc5a43df2eaf0eb1d65438e Mon Sep 17 00:00:00 2001
From: Rob Clark <robdclark@xxxxxxxxxxxx>
Date: Fri, 16 Dec 2022 15:33:55 -0800
Subject: drm/virtio: Fix GEM handle creation UAF
From: Rob Clark <robdclark@xxxxxxxxxxxx>
commit 52531258318ed59a2dc5a43df2eaf0eb1d65438e upstream.
Userspace can guess the handle value and try to race GEM object creation
with handle close, resulting in a use-after-free if we dereference the
object after dropping the handle's reference. For that reason, dropping
the handle's reference must be done *after* we are done dereferencing
the object.
Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
Reviewed-by: Chia-I Wu <olvaffe@xxxxxxxxx>
Fixes: 62fb7a5e1096 ("virtio-gpu: add 3d/virgl support")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20221216233355.542197-2-robdclark@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/virtio/virtgpu_ioctl.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -292,10 +292,18 @@ static int virtio_gpu_resource_create_io
drm_gem_object_release(obj);
return ret;
}
- drm_gem_object_put(obj);
rc->res_handle = qobj->hw_res_handle; /* similiar to a VM address */
rc->bo_handle = handle;
+
+ /*
+ * The handle owns the reference now. But we must drop our
+ * remaining reference *after* we no longer need to dereference
+ * the obj. Otherwise userspace could guess the handle and
+ * race closing it from another thread.
+ */
+ drm_gem_object_put(obj);
+
return 0;
}
@@ -656,11 +664,18 @@ static int virtio_gpu_resource_create_bl
drm_gem_object_release(obj);
return ret;
}
- drm_gem_object_put(obj);
rc_blob->res_handle = bo->hw_res_handle;
rc_blob->bo_handle = handle;
+ /*
+ * The handle owns the reference now. But we must drop our
+ * remaining reference *after* we no longer need to dereference
+ * the obj. Otherwise userspace could guess the handle and
+ * race closing it from another thread.
+ */
+ drm_gem_object_put(obj);
+
return 0;
}
Patches currently in stable-queue which might be from robdclark@xxxxxxxxxxxx are
queue-5.15/drm-virtio-fix-gem-handle-creation-uaf.patch
