1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
|
x86/emulate: check cpl for all privileged instructions
Without this, it is possible for userspace to load its own IDT or GDT.
This is XSA-105.
Reported-by: Andrei LUTAS <vlutas@bitdefender.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Andrei LUTAS <vlutas@bitdefender.com>
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -3314,6 +3314,7 @@ x86_emulate(
goto swint;
case 0xf4: /* hlt */
+ generate_exception_if(!mode_ring0(), EXC_GP, 0);
ctxt->retire.flags.hlt = 1;
break;
@@ -3710,6 +3711,7 @@ x86_emulate(
break;
case 2: /* lgdt */
case 3: /* lidt */
+ generate_exception_if(!mode_ring0(), EXC_GP, 0);
generate_exception_if(ea.type != OP_MEM, EXC_UD, -1);
fail_if(ops->write_segment == NULL);
memset(®, 0, sizeof(reg));
@@ -3738,6 +3740,7 @@ x86_emulate(
case 6: /* lmsw */
fail_if(ops->read_cr == NULL);
fail_if(ops->write_cr == NULL);
+ generate_exception_if(!mode_ring0(), EXC_GP, 0);
if ( (rc = ops->read_cr(0, &cr0, ctxt)) )
goto done;
if ( ea.type == OP_REG )
|
