Merge tag 'drm/gem-cma/for-3.19-rc1' of git://people.freedesktop.org/~tagr/linux into drm-next

drm: Sanitize DRM_IOCTL_MODE_CREATE_DUMB input

Some drivers erroneously treat the .pitch and .size fields of struct
drm_mode_create_dumb as inputs. While the include/uapi/drm/drm_mode.h
header has a comment denoting them as outputs, that seemingly wasn't
enough to make drivers use them properly.

The result is that some userspace doesn't explicitly zero out those
fields, assuming that the kernel won't use them. That causes problems
since the data within the structure might be uninitialized, so bogus
data may end up confusing drivers (ridiculously large values for the
pitch, ...).

This series attempts to improve the situation by fixing all drivers to
not use the output fields. Furthermore to spare new drivers this bad
surprise, the DRM core now zeros out these fields prior to handing the
data structure to the driver.

Lessons learned from this are that future IOCTLs should be properly
documented (in the DRM DocBook for example) and should be rigorously
defined. To prevent misuse like this, userspace should be required to
zero out all output fields. The kernel should check for this and fail
if that's not the case.

* tag 'drm/gem-cma/for-3.19-rc1' of git://people.freedesktop.org/~tagr/linux:
  drm/cma: Remove call to drm_gem_free_mmap_offset()
  drm: Sanitize DRM_IOCTL_MODE_CREATE_DUMB input
  drm/rcar: gem: dumb: pitch is an output
  drm/omap: gem: dumb: pitch is an output
  drm/cma: Introduce drm_gem_cma_dumb_create_internal()
  drm/doc: Add GEM/CMA helpers to kerneldoc
  drm/doc: mm: Fix indentation
  drm/gem: Fix a few kerneldoc typos

1 files changed, 22 insertions, 8 deletions

diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
index 2ff35f3de9c5..acd6af8a8e67 100644
--- a/include/drm/drm_gem_cma_helper.h
+++ b/include/drm/drm_gem_cma_helper.h
@@ -4,6 +4,13 @@
 #include <drm/drmP.h>
 #include <drm/drm_gem.h>
 
+/**
+ * struct drm_gem_cma_object - GEM object backed by CMA memory allocations
+ * @base: base GEM object
+ * @paddr: physical address of the backing memory
+ * @sgt: scatter/gather table for imported PRIME buffers
+ * @vaddr: kernel virtual address of the backing memory
+ */
 struct drm_gem_cma_object {
 	struct drm_gem_object base;
 	dma_addr_t paddr;
@@ -19,23 +26,30 @@ to_drm_gem_cma_obj(struct drm_gem_object *gem_obj)
 	return container_of(gem_obj, struct drm_gem_cma_object, base);
 }
 
-/* free gem object. */
+/* free GEM object */
 void drm_gem_cma_free_object(struct drm_gem_object *gem_obj);
 
-/* create memory region for drm framebuffer. */
+/* create memory region for DRM framebuffer */
+int drm_gem_cma_dumb_create_internal(struct drm_file *file_priv,
+				     struct drm_device *drm,
+				     struct drm_mode_create_dumb *args);
+
+/* create memory region for DRM framebuffer */
 int drm_gem_cma_dumb_create(struct drm_file *file_priv,
-		struct drm_device *drm, struct drm_mode_create_dumb *args);
+			    struct drm_device *drm,
+			    struct drm_mode_create_dumb *args);
 
-/* map memory region for drm framebuffer to user space. */
+/* map memory region for DRM framebuffer to user space */
 int drm_gem_cma_dumb_map_offset(struct drm_file *file_priv,
-		struct drm_device *drm, uint32_t handle, uint64_t *offset);
+				struct drm_device *drm, u32 handle,
+				u64 *offset);
 
-/* set vm_flags and we can change the vm attribute to other one at here. */
+/* set vm_flags and we can change the VM attribute to other one at here */
 int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma);
 
-/* allocate physical memory. */
+/* allocate physical memory */
 struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
-		unsigned int size);
+					      size_t size);
 
 extern const struct vm_operations_struct drm_gem_cma_vm_ops;