On Fri, 19 Jun 2026 at 01:32, Ackerley Tng via B4 Relay <[email protected]> wrote: > > From: Sean Christopherson <[email protected]> > > Check that a valid fd provided to mmap() must be accompanied by MAP_SHARED. > > With an invalid fd (usually used for anonymous mappings), there are no > constraints on mmap() flags. > > Add this check to make sure that when a guest_memfd is used as region->fd, > the flag provided to mmap() will include MAP_SHARED. > > Signed-off-by: Sean Christopherson <[email protected]> > [Rephrase assertion message.] > Signed-off-by: Ackerley Tng <[email protected]>
Reviewed-by: Fuad Tabba <[email protected]> Cheers, /fuad > --- > tools/testing/selftests/kvm/lib/kvm_util.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c > b/tools/testing/selftests/kvm/lib/kvm_util.c > index 0b2256ea65ff9..6b304e8a0e0d5 100644 > --- a/tools/testing/selftests/kvm/lib/kvm_util.c > +++ b/tools/testing/selftests/kvm/lib/kvm_util.c > @@ -1110,6 +1110,9 @@ void vm_mem_add(struct kvm_vm *vm, enum > vm_mem_backing_src_type src_type, > src_type == > VM_MEM_SRC_SHARED_HUGETLB); > } > > + TEST_ASSERT(region->fd == -1 || backing_src_is_shared(src_type), > + "A valid fd provided to mmap() must be accompanied by > MAP_SHARED."); > + > region->mmap_start = __kvm_mmap(region->mmap_size, PROT_READ | > PROT_WRITE, > > vm_mem_backing_src_alias(src_type)->flag, > region->fd, mmap_offset); > > -- > 2.55.0.rc0.738.g0c8ab3ebcc-goog > >
