From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
Dan Carpenter reported that the untrusted data returns from kvm_register_read()
results in the following static checker warning:
arch/x86/kvm/lapic.c:576 kvm_pv_send_ipi()
error: buffer underflow 'map->phys_map' 's32min-s32max'
KVM guest can easily trigger this by executing the following assembly sequence
in Ring0:
mov $10, %rax
mov $0xFFFFFFFF, %rbx
mov $0xFFFFFFFF, %rdx
mov $0, %rsi
vmcall
As this will cause KVM to execute the following code-path:
vmx_handle_exit() -> handle_vmcall() -> kvm_emulate_hypercall() -> kvm_pv_send_ipi()
which will reach out-of-bounds access.
This patch adds the testcase to kvm-unit-tests.
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Cc: Liran Alon <liran.alon@xxxxxxxxxx>
Reviewed-By: Liran Alon <liran.alon@xxxxxxxxxx>
Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
---
v1 -> v2:
* add more changelog
* arguments are documented in Documentation/virtual/kvm/hypercalls.txt
* Define KVM_HC_SEND_IPI instead of using hard-coded
x86/apic.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/x86/apic.c b/x86/apic.c
index c976e8d..6c6ed20 100644
--- a/x86/apic.c
+++ b/x86/apic.c
@@ -566,6 +566,17 @@ static void test_apic_change_mode(void)
report("TMCCT should stay at zero", !apic_read(APIC_TMCCT));
}
+#define KVM_HC_SEND_IPI 10
+
+void test_pv_ipi()
+{
+ int ret;
+ unsigned long a0 = 0xFFFFFFFF, a1 = 0, a2 = 0xFFFFFFFF, a3 = 0x0;
+
+ asm volatile("vmcall" : "=a"(ret) :"a"(KVM_HC_SEND_IPI), "b"(a0), "c"(a1), "d"(a2), "S"(a3));
+ report("PV IPIs testing", !ret);
+}
+
int main(void)
{
setup_vm();
@@ -581,6 +592,7 @@ int main(void)
test_self_ipi();
test_physical_broadcast();
+ test_pv_ipi();
test_sti_nmi();
test_multiple_nmi();
--
2.7.4
