drm/msm: Ensure mmap offset is initialized

If a GEM object is allocated, and then exported as a dma-buf fd which is
mmap'd before or without the GEM buffer being directly mmap'd, the
vma_node could be unitialized.  This leads to a situation where the CPU
mapping is not correctly torn down in drm_vma_node_unmap().

Fixes: e5516553999f ("drm: call drm_gem_object_funcs.mmap with fake offset")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20220531200857.136547-1-robdclark@gmail.com

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 4448536..14ab9a6 100644 (file)
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -964,7 +964,7 @@ static const struct drm_driver msm_driver = {
        .prime_handle_to_fd = drm_gem_prime_handle_to_fd,
        .prime_fd_to_handle = drm_gem_prime_fd_to_handle,
        .gem_prime_import_sg_table = msm_gem_prime_import_sg_table,
-       .gem_prime_mmap     = drm_gem_prime_mmap,
+       .gem_prime_mmap     = msm_gem_prime_mmap,
 #ifdef CONFIG_DEBUG_FS
        .debugfs_init       = msm_debugfs_init,
 #endif

diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h
index fdbaad5..34f74d4 100644 (file)
--- a/drivers/gpu/drm/msm/msm_drv.h
+++ b/drivers/gpu/drm/msm/msm_drv.h
@@ -246,6 +246,7 @@ unsigned long msm_gem_shrinker_shrink(struct drm_device *dev, unsigned long nr_t
 void msm_gem_shrinker_init(struct drm_device *dev);
 void msm_gem_shrinker_cleanup(struct drm_device *dev);
 
+int msm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma);
 struct sg_table *msm_gem_prime_get_sg_table(struct drm_gem_object *obj);
 int msm_gem_prime_vmap(struct drm_gem_object *obj, struct iosys_map *map);
 void msm_gem_prime_vunmap(struct drm_gem_object *obj, struct iosys_map *map);

diff --git a/drivers/gpu/drm/msm/msm_gem_prime.c b/drivers/gpu/drm/msm/msm_gem_prime.c
index 94ab705..dcc8a57 100644 (file)
--- a/drivers/gpu/drm/msm/msm_gem_prime.c
+++ b/drivers/gpu/drm/msm/msm_gem_prime.c
@@ -11,6 +11,21 @@
 #include "msm_drv.h"
 #include "msm_gem.h"
 
+int msm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
+{
+       int ret;
+
+       /* Ensure the mmap offset is initialized.  We lazily initialize it,
+        * so if it has not been first mmap'd directly as a GEM object, the
+        * mmap offset will not be already initialized.
+        */
+       ret = drm_gem_create_mmap_offset(obj);
+       if (ret)
+               return ret;
+
+       return drm_gem_prime_mmap(obj, vma);
+}
+
 struct sg_table *msm_gem_prime_get_sg_table(struct drm_gem_object *obj)
 {
        struct msm_gem_object *msm_obj = to_msm_bo(obj);