diff options
| author | Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> | 2018-05-22 17:13:04 +0300 |
|---|---|---|
| committer | Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com> | 2018-05-31 10:36:28 +0300 |
| commit | 069035c5db3459b9b5f12caf3bffed9a863fa5c4 (patch) | |
| tree | f32b505ef20d1e6dba33220a5681fd71b330344d /drivers/gpu/drm/drm_drv.c | |
| parent | fbecef131676c1d18e8e6b42c04e10dc49725e96 (diff) | |
| download | linux-069035c5db3459b9b5f12caf3bffed9a863fa5c4.tar.xz | |
drm: Fix possible race conditions while unplugging DRM device
When unplugging a hotpluggable DRM device we first unregister it
with drm_dev_unregister and then set drm_device.unplugged flag which
is used to mark device critical sections with drm_dev_enter()/
drm_dev_exit() preventing access to device resources that are not
available after the device is gone.
But drm_dev_unregister may lead to hotplug uevent(s) fired to
user-space on card and/or connector removal, thus making it possible
for user-space to try accessing a disconnected device.
Fix this by first making sure device is properly marked as
disconnected and only then unregister it.
Fixes: bee330f3d672 ("drm: Use srcu to protect drm_device.unplugged")
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reported-by: Andrii Chepurnyi <andrii_chepurnyi@epam.com>
Cc: "Noralf Trønnes" <noralf@tronnes.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180522141304.18646-1-andr2000@gmail.com
Diffstat (limited to 'drivers/gpu/drm/drm_drv.c')
| -rw-r--r-- | drivers/gpu/drm/drm_drv.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c index f6910ebe4d0e..cc2675550e28 100644 --- a/drivers/gpu/drm/drm_drv.c +++ b/drivers/gpu/drm/drm_drv.c @@ -369,13 +369,6 @@ EXPORT_SYMBOL(drm_dev_exit); */ void drm_dev_unplug(struct drm_device *dev) { - drm_dev_unregister(dev); - - mutex_lock(&drm_global_mutex); - if (dev->open_count == 0) - drm_dev_put(dev); - mutex_unlock(&drm_global_mutex); - /* * After synchronizing any critical read section is guaranteed to see * the new value of ->unplugged, and any critical section which might @@ -384,6 +377,13 @@ void drm_dev_unplug(struct drm_device *dev) */ dev->unplugged = true; synchronize_srcu(&drm_unplug_srcu); + + drm_dev_unregister(dev); + + mutex_lock(&drm_global_mutex); + if (dev->open_count == 0) + drm_dev_put(dev); + mutex_unlock(&drm_global_mutex); } EXPORT_SYMBOL(drm_dev_unplug); |