In the SET_GLOBAL ioctl, v3d_perfmon_find() bumps the reference count on
the perfmon it returns, but v3d_perfmon_set_global_ioctl() and
v3d_perfmon_delete() fail to release that reference on several paths:
1. v3d_perfmon_set_global_ioctl() leaks the reference on its error
paths.
2. CLEAR_GLOBAL leaks both the find reference and the reference
previously stashed in v3d->global_perfmon by the SET_GLOBAL ioctl
that configured it.
3. Destroying a perfmon that is the current global perfmon leaks the
reference stashed by the SET_GLOBAL ioctl.
Release each of these references explicitly.
Cc: [email protected]
Fixes: c6eabbab359c ("drm/v3d: Add DRM_IOCTL_V3D_PERFMON_SET_GLOBAL")
Signed-off-by: Maíra Canal <[email protected]>
---
drivers/gpu/drm/v3d/v3d_perfmon.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/v3d/v3d_perfmon.c
b/drivers/gpu/drm/v3d/v3d_perfmon.c
index 02451fc09dbb..48ae748247be 100644
--- a/drivers/gpu/drm/v3d/v3d_perfmon.c
+++ b/drivers/gpu/drm/v3d/v3d_perfmon.c
@@ -319,8 +319,11 @@ static void v3d_perfmon_delete(struct v3d_file_priv
*v3d_priv,
if (perfmon == v3d->active_perfmon)
v3d_perfmon_stop(v3d, perfmon, false);
- /* If the global perfmon is being destroyed, set it to NULL */
- cmpxchg(&v3d->global_perfmon, perfmon, NULL);
+ /* If the global perfmon is being destroyed, clean it and release
+ * the reference stashed in v3d_perfmon_set_global_ioctl().
+ */
+ if (cmpxchg(&v3d->global_perfmon, perfmon, NULL) == perfmon)
+ v3d_perfmon_put(perfmon);
v3d_perfmon_put(perfmon);
}
@@ -471,16 +474,27 @@ int v3d_perfmon_set_global_ioctl(struct drm_device *dev,
void *data,
/* If the request is to clear the global performance monitor */
if (req->flags & DRM_V3D_PERFMON_CLEAR_GLOBAL) {
- if (!v3d->global_perfmon)
+ struct v3d_perfmon *old;
+
+ /* DRM_V3D_PERFMON_CLEAR_GLOBAL doesn't check if
+ * v3d->global_perfmon == perfmon. Therefore, there
+ * is no need to keep perfmon's reference.
+ */
+ v3d_perfmon_put(perfmon);
+
+ old = xchg(&v3d->global_perfmon, NULL);
+ if (!old)
return -EINVAL;
- xchg(&v3d->global_perfmon, NULL);
+ v3d_perfmon_put(old);
return 0;
}
- if (cmpxchg(&v3d->global_perfmon, NULL, perfmon))
+ if (cmpxchg(&v3d->global_perfmon, NULL, perfmon)) {
+ v3d_perfmon_put(perfmon);
return -EBUSY;
+ }
return 0;
}
--
2.54.0
