The BOs created with DRM_PANTHOR_BO_NO_MMAP flag are not supposed to be
mmappable by the Userspace. But after the rework to support shrinker,
it became possible to mmap NO_MMAP BOs. Userspace could second guess
the file offset range, allocated unconditionally at the BO creation
time, and create a CPU mapping. There may not be any adverse effect of
such a CPU mapping though.
This commit adds a check in the mmap callback of Panthor driver to
fail the mmap() attempts on BOs created with NO_MMAP flag. The check
covers private BOs as well as the prime exported BOs that are mmapped
using prime fd.
v2:
- Fix breakage of mmap() on exported BOs that didn't have
BO_MMAP_OFFSET ioctl invoked for them.
Fixes: 68cbf96b1e9b ("drm/panthor: Part ways with drm_gem_shmem_object")
Suggested-by: Boris Brezillon <[email protected]>
Signed-off-by: Akash Goel <[email protected]>
---
drivers/gpu/drm/panthor/panthor_gem.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/panthor/panthor_gem.c
b/drivers/gpu/drm/panthor/panthor_gem.c
index c07a44057e42..22b57ab6f929 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.c
+++ b/drivers/gpu/drm/panthor/panthor_gem.c
@@ -744,6 +744,9 @@ static int panthor_gem_mmap(struct drm_gem_object *obj,
struct vm_area_struct *v
struct panthor_gem_object *bo = to_panthor_bo(obj);
int ret;
+ if (bo->flags & DRM_PANTHOR_BO_NO_MMAP)
+ return -EINVAL;
+
if (drm_gem_is_imported(obj)) {
/* Reset both vm_ops and vm_private_data, so we don't end up
with
* vm_ops pointing to our implementation if the dma-buf backend
--
2.25.1
