[PATCH v2 01/11] KVM: x86: emulator: em_sysexit should update ctxt->mode

Maxim Levitsky
2022-06-21T15:09:27Z

This is one of the instructions that can change the
processor mode.

Note that this is likely a benign bug, because the only problematic
mode change is from 32 bit to 64 bit which can lead to truncation of RIP,
and it is not possible to do with sysexit,
since sysexit running in 32 bit mode will be limited to 32 bit version.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/emulate.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 39ea9138224c62..5aeb343ca8b007 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2888,6 +2888,7 @@ static int em_sysexit(struct x86_emulate_ctxt *ctxt)
ops->set_segment(ctxt, ss_sel, &ss, 0, VCPU_SREG_SS);

ctxt->_eip = rdx;
+ ctxt->mode = usermode;
*reg_write(ctxt, VCPU_REGS_RSP) = rcx;

return X86EMUL_CONTINUE;
--
2.26.3