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KVM: x86: emulator: em_sysexit should update ctxt->mode
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commit 5015bb8 upstream.

SYSEXIT is one of the instructions that can change the
processor mode, thus ctxt->mode should be updated after it.

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>
Message-Id: <20221025124741.228045-11-mlevitsk@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Maxim Levitsky authored and Greg Kroah-Hartman committed Nov 10, 2022
1 parent 838852a commit 03dce7d
Showing 1 changed file with 1 addition and 0 deletions.
1 change: 1 addition & 0 deletions arch/x86/kvm/emulate.c
Original file line number Diff line number Diff line change
Expand Up @@ -2889,6 +2889,7 @@ 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;
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