[v19,10/15] drm/radeon: untag user pointers in radeon_gem_userptr_ioctl

Commit Message

Andrey Konovalov July 23, 2019, 5:58 p.m. UTC

This patch is a part of a series that extends kernel ABI to allow to pass
tagged user pointers (with the top byte set to something else other than
0x00) as syscall arguments.

In radeon_gem_userptr_ioctl() an MMU notifier is set up with a (tagged)
userspace pointer. The untagged address should be used so that MMU
notifiers for the untagged address get correctly matched up with the right
BO. This funcation also calls radeon_ttm_tt_pin_userptr(), which uses
provided user pointers for vma lookups, which can only by done with
untagged pointers.

This patch untags user pointers in radeon_gem_userptr_ioctl().

Reviewed-by: Khalid Aziz <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>
Suggested-by: Felix Kuehling <[e-mail]>
Acked-by: Felix Kuehling <[e-mail]>
Signed-off-by: Andrey Konovalov <[e-mail]>
---
 drivers/gpu/drm/radeon/radeon_gem.c | 2 ++
 1 file changed, 2 insertions(+)

Patch

diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
index d8bc5d2dfd61..89353098b627 100644
--- a/drivers/gpu/drm/radeon/radeon_gem.c
+++ b/drivers/gpu/drm/radeon/radeon_gem.c
@@ -296,6 +296,8 @@  int radeon_gem_userptr_ioctl(struct drm_device *dev, void *data,
 	uint32_t handle;
 	int r;
 
+	args->addr = untagged_addr(args->addr);
+
 	if (offset_in_page(args->addr | args->size))
 		return -EINVAL;