Author: emaste
Date: Tue Sep 15 21:04:27 2020
New Revision: 365775
URL: https://svnweb.freebsd.org/changeset/base/365775
Log:
bhyve: do not permit write access to VMCB / VMCS
Reported by: Patrick Mooney
Submitted by: jhb
Security: CVE-2020-24718
Modified:
head/sys/amd64/vmm/amd/svm.c
head/sys/amd64/vmm/intel/vmx.c
Modified: head/sys/amd64/vmm/amd/svm.c
==============================================================================
--- head/sys/amd64/vmm/amd/svm.c Tue Sep 15 21:00:25 2020
(r365774)
+++ head/sys/amd64/vmm/amd/svm.c Tue Sep 15 21:04:27 2020
(r365775)
@@ -2227,8 +2227,11 @@ svm_setreg(void *arg, int vcpu, int ident, uint64_t va
return (svm_modify_intr_shadow(svm_sc, vcpu, val));
}
- if (vmcb_write(svm_sc, vcpu, ident, val) == 0) {
- return (0);
+ /* Do not permit user write access to VMCB fields by offset. */
+ if (!VMCB_ACCESS_OK(ident)) {
+ if (vmcb_write(svm_sc, vcpu, ident, val) == 0) {
+ return (0);
+ }
}
reg = swctx_regptr(svm_get_guest_regctx(svm_sc, vcpu), ident);
Modified: head/sys/amd64/vmm/intel/vmx.c
==============================================================================
--- head/sys/amd64/vmm/intel/vmx.c Tue Sep 15 21:00:25 2020
(r365774)
+++ head/sys/amd64/vmm/intel/vmx.c Tue Sep 15 21:04:27 2020
(r365775)
@@ -3341,6 +3341,10 @@ vmx_setreg(void *arg, int vcpu, int reg, uint64_t val)
if (vmxctx_setreg(&vmx->ctx[vcpu], reg, val) == 0)
return (0);
+ /* Do not permit user write access to VMCS fields by offset. */
+ if (reg < 0)
+ return (EINVAL);
+
error = vmcs_setreg(&vmx->vmcs[vcpu], running, reg, val);
if (error == 0) {
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