[Xen-devel] [PATCH for-4.8] x86/emul: Reject LGDT/LIDT attempts with non-canonical base addresses

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

No sane OS would deliberately try this, but make Xen's emulation match real
hardware by delivering #GP(0), rather than suffering a VMEntry failure.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/arch/x86/x86_emulate/x86_emulate.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 7a707dc..6b940c4 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -4443,6 +4443,8 @@ x86_emulate(
                  (rc = read_ulong(ea.mem.seg, ea.mem.off+2,
                                   &base, mode_64bit() ? 8 : 4, ctxt, ops)) )
                 goto done;
+            generate_exception_if(mode_64bit() &&
+                                  !is_canonical_address(base), EXC_GP, 0);
             sreg.base = base;
             sreg.limit = limit;
             if ( op_bytes == 2 )
-- 
2.1.4


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