KVM: add missing compat KVM_CLEAR_DIRTY_LOG

The arguments to the KVM_CLEAR_DIRTY_LOG ioctl include a pointer,
therefore it needs a compat ioctl implementation.  Otherwise,
32-bit userspace fails to invoke it on 64-bit kernels; for x86
it might work fine by chance if the padding is zero, but not
on big-endian architectures.

Reported-by: Thomas Sattler
Cc: stable@vger.kernel.org
Fixes: 2a31b9db1535 ("kvm: introduce manual dirty log reprotect")
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0d732813fa80ba9faa4d10141933ca50ec7b6286..d20fba0fc290333865c5e65f700a466bf24b0439 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4391,6 +4391,16 @@ struct compat_kvm_dirty_log {
        };
 };
 
+struct compat_kvm_clear_dirty_log {
+       __u32 slot;
+       __u32 num_pages;
+       __u64 first_page;
+       union {
+               compat_uptr_t dirty_bitmap; /* one bit per page */
+               __u64 padding2;
+       };
+};
+
 static long kvm_vm_compat_ioctl(struct file *filp,
                           unsigned int ioctl, unsigned long arg)
 {
@@ -4400,6 +4410,24 @@ static long kvm_vm_compat_ioctl(struct file *filp,
        if (kvm->mm != current->mm)
                return -EIO;
        switch (ioctl) {
+#ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
+       case KVM_CLEAR_DIRTY_LOG: {
+               struct compat_kvm_clear_dirty_log compat_log;
+               struct kvm_clear_dirty_log log;
+
+               if (copy_from_user(&compat_log, (void __user *)arg,
+                                  sizeof(compat_log)))
+                       return -EFAULT;
+               log.slot         = compat_log.slot;
+               log.num_pages    = compat_log.num_pages;
+               log.first_page   = compat_log.first_page;
+               log.padding2     = compat_log.padding2;
+               log.dirty_bitmap = compat_ptr(compat_log.dirty_bitmap);
+
+               r = kvm_vm_ioctl_clear_dirty_log(kvm, &log);
+               break;
+       }
+#endif
        case KVM_GET_DIRTY_LOG: {
                struct compat_kvm_dirty_log compat_log;
                struct kvm_dirty_log log;