| Message ID | 20210710002837.366942-1-Felix.Kuehling@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/1] drm/ttm: Fix COW check | expand |
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);
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, }; 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);
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(-)