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@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
---
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);
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