This is a note to let you know that I've just added the patch titled KVM: VMX: Don't use vcpu->run->internal.ndata as an array index to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kvm-vmx-don-t-use-vcpu-run-internal.ndata-as-an-arra.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 7ee3fa3365a94f1e81b4ede5029d14ca1f155617 Author: Reiji Watanabe <reijiw@xxxxxxxxxx> Date: Tue Apr 13 15:47:40 2021 +0000 KVM: VMX: Don't use vcpu->run->internal.ndata as an array index [ Upstream commit 04c4f2ee3f68c9a4bf1653d15f1a9a435ae33f7a ] __vmx_handle_exit() uses vcpu->run->internal.ndata as an index for an array access. Since vcpu->run is (can be) mapped to a user address space with a writer permission, the 'ndata' could be updated by the user process at anytime (the user process can set it to outside the bounds of the array). So, it is not safe that __vmx_handle_exit() uses the 'ndata' that way. Fixes: 1aa561b1a4c0 ("kvm: x86: Add "last CPU" to some KVM_EXIT information") Signed-off-by: Reiji Watanabe <reijiw@xxxxxxxxxx> Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx> Message-Id: <20210413154739.490299-1-reijiw@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 880a2617820c..95f836fbceb2 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -5986,19 +5986,19 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath) exit_reason.basic != EXIT_REASON_PML_FULL && exit_reason.basic != EXIT_REASON_APIC_ACCESS && exit_reason.basic != EXIT_REASON_TASK_SWITCH)) { + int ndata = 3; + vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_DELIVERY_EV; - vcpu->run->internal.ndata = 3; vcpu->run->internal.data[0] = vectoring_info; vcpu->run->internal.data[1] = exit_reason.full; vcpu->run->internal.data[2] = vcpu->arch.exit_qualification; if (exit_reason.basic == EXIT_REASON_EPT_MISCONFIG) { - vcpu->run->internal.ndata++; - vcpu->run->internal.data[3] = + vcpu->run->internal.data[ndata++] = vmcs_read64(GUEST_PHYSICAL_ADDRESS); } - vcpu->run->internal.data[vcpu->run->internal.ndata++] = - vcpu->arch.last_vmentry_cpu; + vcpu->run->internal.data[ndata++] = vcpu->arch.last_vmentry_cpu; + vcpu->run->internal.ndata = ndata; return 0; }