Am 10.07.21 um 02:28 schrieb Felix Kuehling:

KFD Thunk maps invisible VRAM BOs with PROT_NONE, MAP_PRIVATE. is_cow_mapping returns true for these mappings. Add a check for vm_flags & VM_WRITE to avoid mmap failures on private read-only or PROT_NONE mappings.

v2: protect against mprotect making a mapping writable after the fact

Fixes: f91142c62161 ("drm/ttm: nuke VM_MIXEDMAP on BO mappings v3") Signed-off-by: Felix Kuehling Felix.Kuehling@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com

---

drivers/gpu/drm/ttm/ttm_bo_vm.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c index f56be5bc0861..9ad211ede611 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c @@ -542,17 +542,28 @@ int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr, } EXPORT_SYMBOL(ttm_bo_vm_access);

+static int ttm_bo_vm_mprotect(struct vm_area_struct *vma, unsigned long start,

• 	      unsigned long end, unsigned long newflags)
  

+{

• /* Enforce no COW since would have really strange behavior with it. */
• if (is_cow_mapping(newflags) && (newflags & VM_WRITE))

• return -EINVAL;
  

• return 0;

+}

• static const struct vm_operations_struct ttm_bo_vm_ops = { .fault = ttm_bo_vm_fault, .open = ttm_bo_vm_open, .close = ttm_bo_vm_close, .access = ttm_bo_vm_access,
• .mprotect = ttm_bo_vm_mprotect,

The problem is most drivers implement their own copy of this structure.

You need to add this to those occasions as well, just search for references to ttm_bo_vm_open.

Regards, Christian.

};

int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *bo) { /* Enforce no COW since would have really strange behavior with it. */

• if (is_cow_mapping(vma->vm_flags))

• if (is_cow_mapping(vma->vm_flags) && (vma->vm_flags & VM_WRITE)) return -EINVAL;

  ttm_bo_get(bo);