Subject: CVE-2022-48764: KVM: x86: Free kvm_cpuid_entry2 array on post-KVM_RUN KVM_SET_CPUID{,2}

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

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

The Linux kernel CVE team has assigned CVE-2022-48764 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 5.16.3 with commit 24e7590c60aa and fixed in 5.16.5 with commit b9ee734a14bb

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-48764
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	arch/x86/kvm/cpuid.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/b9ee734a14bb685b2088f2176d82b34cb4e30dbc
	https://git.kernel.org/stable/c/811f95ff95270e6048197821434d9301e3d7f07c