@@ -1941,12 +1941,22 @@ int __kvm_set_memory_region(struct kvm *kvm,
return -EINVAL;
if (mem->guest_phys_addr & (PAGE_SIZE - 1))
return -EINVAL;
+
+ /* Serialize against tagging enabling */
+ if (mmap_read_lock_killable(kvm->mm))
+ return -EINTR;
+
/* We can read the guest memory with __xxx_user() later on. */
if ((mem->userspace_addr & (PAGE_SIZE - 1)) ||
(mem->userspace_addr != untagged_addr(kvm->mm, mem->userspace_addr)) ||
!access_ok((void __user *)(unsigned long)mem->userspace_addr,
- mem->memory_size))
+ mem->memory_size)) {
+ mmap_read_unlock(kvm->mm);
return -EINVAL;
+ }
+
+ mmap_read_unlock(kvm->mm);
+
if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM)
return -EINVAL;
if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
KVM forbids usage of tagged userspace addresses for memslots. It is done by checking if the address stays the same after untagging. It is works fine for ARM TBI, but it the check gets racy for LAM. TBI enabling happens per-thread, so nobody can enable tagging for the thread while the memslot gets added. LAM gets enabled per-process. If it gets enabled after the untagged_addr() check, but before access_ok() check the kernel can wrongly allow tagged userspace_addr. Use mmap lock to protect against parallel LAM enabling. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Cc: Marc Zyngier <maz@kernel.org> --- virt/kvm/kvm_main.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)