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UPSTREAM: drm/virtio: Ensure cached capset entries are valid before copying.

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virtio_gpu_get_caps_ioctl could return success with invalid data if a
second caller to the function occurred after the entry was created in
virtio_gpu_cmd_get_capset but prior to the virtio_gpu_cmd_capset_cb
callback being called.  This could leak contents of memory as well
since the caps_cache allocation is done without zeroing.

Signed-off-by: David Riley <davidriley@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20190605234423.11348-1-davidriley@chromium.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit 7fdf478a43869bee27e1b50955830f6ebc730b67)
Signed-off-by: Greg Hartman <ghartman@google.com>
BUG: 139386237
Change-Id: I4b984184f3ad77cc48e2d449abc031d1dc8530bd
This commit is contained in:
David Riley 2019-06-05 16:44:20 -07:00 committed by Alistair Delva
parent 72ace7ce28
commit bc371c3453
1 changed files with 1 additions and 2 deletions
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3
drivers/gpu/drm/virtio/virtgpu_ioctl.c
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@ -524,7 +524,6 @@ static int virtio_gpu_get_caps_ioctl(struct drm_device *dev,
list_for_each_entry(cache_ent, &vgdev->cap_cache, head) {
if (cache_ent->id == args->cap_set_id &&
cache_ent->version == args->cap_set_ver) {
ptr = cache_ent->caps_cache;
spin_unlock(&vgdev->display_info_lock);
goto copy_exit;
}
@ -535,6 +534,7 @@ static int virtio_gpu_get_caps_ioctl(struct drm_device *dev,
virtio_gpu_cmd_get_capset(vgdev, found_valid, args->cap_set_ver,
&cache_ent);
copy_exit:
ret = wait_event_timeout(vgdev->resp_wq,
atomic_read(&cache_ent->is_valid), 5 * HZ);
if (!ret)
@ -545,7 +545,6 @@ static int virtio_gpu_get_caps_ioctl(struct drm_device *dev,
ptr = cache_ent->caps_cache;
copy_exit:
if (copy_to_user(u64_to_user_ptr(args->addr), ptr, size))
return -EFAULT;