[PATCH 5.13 009/104] KVM: add missing compat KVM_CLEAR_DIRTY_LOG

Greg Kroah-Hartman
2021-08-02T14:05:30Z

From: Paolo Bonzini <pbonzini@redhat.com>

commit 8750f9bbda115f3f79bfe43be85551ee5e12b6ff upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
virt/kvm/kvm_main.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4183,6 +4183,16 @@ 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)
{
@@ -4192,6 +4202,24 @@ static long kvm_vm_compat_ioctl(struct f
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;