KVM: x86: Free kvm_cpuid_entry2 array on post-KVM_RUN KVM_SET_CPUID{,2}

In the Linux kernel, the following vulnerability has been resolved:

KVM: x86: Free kvm_cpuid_entry2 array on post-KVM_RUN KVM_SET_CPUID{,2}

Free the "struct kvm_cpuid_entry2" array on successful post-KVM_RUN
KVM_SET_CPUID{,2} to fix a memory leak, the callers of kvm_set_cpuid()
free the array only on failure.

BUG: memory leak
unreferenced object 0xffff88810963a800 (size 2048):
comm "syz-executor025", pid 3610, jiffies 4294944928 (age 8.080s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 0d 00 00 00 ................
47 65 6e 75 6e 74 65 6c 69 6e 65 49 00 00 00 00 GenuntelineI....
backtrace:
[<ffffffff814948ee>] kmalloc_node include/linux/slab.h:604 [inline]
[<ffffffff814948ee>] kvmalloc_node+0x3e/0x100 mm/util.c:580
[<ffffffff814950f2>] kvmalloc include/linux/slab.h:732 [inline]
[<ffffffff814950f2>] vmemdup_user+0x22/0x100 mm/util.c:199
[<ffffffff8109f5ff>] kvm_vcpu_ioctl_set_cpuid2+0x8f/0xf0 arch/x86/kvm/cpuid.c:423
[<ffffffff810711b9>] kvm_arch_vcpu_ioctl+0xb99/0x1e60 arch/x86/kvm/x86.c:5251
[<ffffffff8103e92d>] kvm_vcpu_ioctl+0x4ad/0x950 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4066
[<ffffffff815afacc>] vfs_ioctl fs/ioctl.c:51 [inline]
[<ffffffff815afacc>] __do_sys_ioctl fs/ioctl.c:874 [inline]
[<ffffffff815afacc>] __se_sys_ioctl fs/ioctl.c:860 [inline]
[<ffffffff815afacc>] __x64_sys_ioctl+0xfc/0x140 fs/ioctl.c:860
[<ffffffff844a3335>] do_syscall_x64 arch/x86/entry/common.c:50 [inline]
[<ffffffff844a3335>] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
[<ffffffff84600068>] entry_SYSCALL_64_after_hwframe+0x44/0xae