| Message ID | 20180928232126.4332-1-eric@anholt.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/4] drm/v3d: Fix a use-after-free race accessing the scheduler's fences. | expand |
On Fri, 28 Sep 2018 16:21:23 -0700 Eric Anholt <eric@anholt.net> wrote: > Once we push the job, the scheduler could run it and free it. So, if > we want to reference their fences, we need to grab them before then. > I haven't seen this happen in many days of conformance test runtime, > but let's still close the race. > > Signed-off-by: Eric Anholt <eric@anholt.net> > Fixes: 57692c94dcbe ("drm/v3d: Introduce a new DRM driver for Broadcom V3D V3.x+") Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com> > --- > drivers/gpu/drm/v3d/v3d_drv.h | 5 +++++ > drivers/gpu/drm/v3d/v3d_gem.c | 8 ++++++-- > 2 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h > index 5042573e97f4..83c55ab6e1c0 100644 > --- a/drivers/gpu/drm/v3d/v3d_drv.h > +++ b/drivers/gpu/drm/v3d/v3d_drv.h > @@ -204,6 +204,11 @@ struct v3d_exec_info { > */ > struct dma_fence *bin_done_fence; > > + /* Fence for when the scheduler considers the render to be > + * done, for when the BOs reservations should be complete. > + */ > + struct dma_fence *render_done_fence; > + > struct kref refcount; > > /* This is the array of BOs that were looked up at the start of exec. */ > diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c > index e1fcbb4cd0ae..c98fbfbdb68e 100644 > --- a/drivers/gpu/drm/v3d/v3d_gem.c > +++ b/drivers/gpu/drm/v3d/v3d_gem.c > @@ -209,7 +209,7 @@ v3d_flush_caches(struct v3d_dev *v3d) > static void > v3d_attach_object_fences(struct v3d_exec_info *exec) > { > - struct dma_fence *out_fence = &exec->render.base.s_fence->finished; > + struct dma_fence *out_fence = exec->render_done_fence; > struct v3d_bo *bo; > int i; > > @@ -409,6 +409,7 @@ v3d_exec_cleanup(struct kref *ref) > dma_fence_put(exec->render.done_fence); > > dma_fence_put(exec->bin_done_fence); > + dma_fence_put(exec->render_done_fence); > > for (i = 0; i < exec->bo_count; i++) > drm_gem_object_put_unlocked(&exec->bo[i]->base); > @@ -574,6 +575,9 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data, > if (ret) > goto fail_unreserve; > > + exec->render_done_fence = > + dma_fence_get(&exec->render.base.s_fence->finished); > + > kref_get(&exec->refcount); /* put by scheduler job completion */ > drm_sched_entity_push_job(&exec->render.base, > &v3d_priv->sched_entity[V3D_RENDER]); > @@ -587,7 +591,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data, > sync_out = drm_syncobj_find(file_priv, args->out_sync); > if (sync_out) { > drm_syncobj_replace_fence(sync_out, > - &exec->render.base.s_fence->finished); > + exec->render_done_fence); > drm_syncobj_put(sync_out); > } >
diff --git a/drivers/gpu/drm/v3d/v3d_drv.h b/drivers/gpu/drm/v3d/v3d_drv.h index 5042573e97f4..83c55ab6e1c0 100644 --- a/drivers/gpu/drm/v3d/v3d_drv.h +++ b/drivers/gpu/drm/v3d/v3d_drv.h @@ -204,6 +204,11 @@ struct v3d_exec_info { */ struct dma_fence *bin_done_fence; + /* Fence for when the scheduler considers the render to be + * done, for when the BOs reservations should be complete. + */ + struct dma_fence *render_done_fence; + struct kref refcount; /* This is the array of BOs that were looked up at the start of exec. */ diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c index e1fcbb4cd0ae..c98fbfbdb68e 100644 --- a/drivers/gpu/drm/v3d/v3d_gem.c +++ b/drivers/gpu/drm/v3d/v3d_gem.c @@ -209,7 +209,7 @@ v3d_flush_caches(struct v3d_dev *v3d) static void v3d_attach_object_fences(struct v3d_exec_info *exec) { - struct dma_fence *out_fence = &exec->render.base.s_fence->finished; + struct dma_fence *out_fence = exec->render_done_fence; struct v3d_bo *bo; int i; @@ -409,6 +409,7 @@ v3d_exec_cleanup(struct kref *ref) dma_fence_put(exec->render.done_fence); dma_fence_put(exec->bin_done_fence); + dma_fence_put(exec->render_done_fence); for (i = 0; i < exec->bo_count; i++) drm_gem_object_put_unlocked(&exec->bo[i]->base); @@ -574,6 +575,9 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data, if (ret) goto fail_unreserve; + exec->render_done_fence = + dma_fence_get(&exec->render.base.s_fence->finished); + kref_get(&exec->refcount); /* put by scheduler job completion */ drm_sched_entity_push_job(&exec->render.base, &v3d_priv->sched_entity[V3D_RENDER]); @@ -587,7 +591,7 @@ v3d_submit_cl_ioctl(struct drm_device *dev, void *data, sync_out = drm_syncobj_find(file_priv, args->out_sync); if (sync_out) { drm_syncobj_replace_fence(sync_out, - &exec->render.base.s_fence->finished); + exec->render_done_fence); drm_syncobj_put(sync_out); }
Once we push the job, the scheduler could run it and free it. So, if we want to reference their fences, we need to grab them before then. I haven't seen this happen in many days of conformance test runtime, but let's still close the race. Signed-off-by: Eric Anholt <eric@anholt.net> Fixes: 57692c94dcbe ("drm/v3d: Introduce a new DRM driver for Broadcom V3D V3.x+") --- drivers/gpu/drm/v3d/v3d_drv.h | 5 +++++ drivers/gpu/drm/v3d/v3d_gem.c | 8 ++++++-- 2 files changed, 11 insertions(+), 2 deletions(-)