[Xen-changelog] [xen stable-4.4] x86emul: only emulate software interrupt injection for real mode

[patchbot@xxxxxxx]

commit a299a3e88a387de88489d6a6f61bebdafc95ebe5
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Sep 23 14:40:51 2014 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Sep 23 14:40:51 2014 +0200

    x86emul: only emulate software interrupt injection for real mode
    
    Protected mode emulation currently lacks proper privilege checking of
    the referenced IDT entry, and there's currently no legitimate way for
    any of the respective instructions to reach the emulator when the guest
    is in protected mode.
    
    This is XSA-106.
    
    Reported-by: Andrei LUTAS <vlutas@xxxxxxxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Keir Fraser <keir@xxxxxxx>
    master commit: 346d4545569928b652c40c7815c1732676f8587c
    master date: 2014-09-23 14:33:50 +0200
---
 xen/arch/x86/x86_emulate/x86_emulate.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 4810e68..5fbe024 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -2634,6 +2634,7 @@ x86_emulate(
     case 0xcd: /* int imm8 */
         src.val = insn_fetch_type(uint8_t);
     swint:
+        fail_if(!in_realmode(ctxt, ops)); /* XSA-106 */
         fail_if(ops->inject_sw_interrupt == NULL);
         rc = ops->inject_sw_interrupt(src.val, _regs.eip - ctxt->regs->eip,
                                       ctxt) ? : X86EMUL_EXCEPTION;
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.4

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