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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen stable-4.9] x86/traps: Use an Interrupt Stack Table for #DB
commit 35a71c61a357fff0ca89e2b7d2e8e2058f7e6db5
Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Tue May 8 18:16:37 2018 +0100
Commit: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue May 8 18:16:37 2018 +0100
x86/traps: Use an Interrupt Stack Table for #DB
PV guests can use architectural corner cases to cause #DB to be raised after
transitioning into supervisor mode.
Use an interrupt stack table for #DB to prevent the exception being taken
with
a guest controlled stack pointer.
This is part of XSA-260 / CVE-2018-8897.
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
xen/arch/x86/cpu/common.c | 2 ++
xen/arch/x86/hvm/svm/svm.c | 2 ++
xen/arch/x86/smpboot.c | 1 +
xen/arch/x86/traps.c | 13 +++++++------
xen/arch/x86/x86_64/entry.S | 2 +-
xen/include/asm-x86/processor.h | 3 ++-
6 files changed, 15 insertions(+), 8 deletions(-)
diff --git a/xen/arch/x86/cpu/common.c b/xen/arch/x86/cpu/common.c
index 0e83a94900..aaaa7850bc 100644
--- a/xen/arch/x86/cpu/common.c
+++ b/xen/arch/x86/cpu/common.c
@@ -679,6 +679,7 @@ void load_system_tables(void)
[IST_MCE - 1] = stack_top + IST_MCE * PAGE_SIZE,
[IST_DF - 1] = stack_top + IST_DF * PAGE_SIZE,
[IST_NMI - 1] = stack_top + IST_NMI * PAGE_SIZE,
+ [IST_DB - 1] = stack_top + IST_DB * PAGE_SIZE,
[IST_MAX ... ARRAY_SIZE(tss->ist) - 1] =
0x8600111111111111ul,
@@ -706,6 +707,7 @@ void load_system_tables(void)
set_ist(&idt_tables[cpu][TRAP_double_fault], IST_DF);
set_ist(&idt_tables[cpu][TRAP_nmi], IST_NMI);
set_ist(&idt_tables[cpu][TRAP_machine_check], IST_MCE);
+ set_ist(&idt_tables[cpu][TRAP_debug], IST_DB);
/*
* Bottom-of-stack must be 16-byte aligned!
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index cb9ebd4642..27c2079ecd 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1048,6 +1048,7 @@ static void svm_ctxt_switch_from(struct vcpu *v)
set_ist(&idt_tables[cpu][TRAP_double_fault], IST_DF);
set_ist(&idt_tables[cpu][TRAP_nmi], IST_NMI);
set_ist(&idt_tables[cpu][TRAP_machine_check], IST_MCE);
+ set_ist(&idt_tables[cpu][TRAP_debug], IST_DB);
}
static void svm_ctxt_switch_to(struct vcpu *v)
@@ -1069,6 +1070,7 @@ static void svm_ctxt_switch_to(struct vcpu *v)
set_ist(&idt_tables[cpu][TRAP_double_fault], IST_NONE);
set_ist(&idt_tables[cpu][TRAP_nmi], IST_NONE);
set_ist(&idt_tables[cpu][TRAP_machine_check], IST_NONE);
+ set_ist(&idt_tables[cpu][TRAP_debug], IST_NONE);
svm_restore_dr(v);
diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index 9e59869735..3d5faa2a09 100644
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -964,6 +964,7 @@ static int cpu_smpboot_alloc(unsigned int cpu)
set_ist(&idt_tables[cpu][TRAP_double_fault], IST_NONE);
set_ist(&idt_tables[cpu][TRAP_nmi], IST_NONE);
set_ist(&idt_tables[cpu][TRAP_machine_check], IST_NONE);
+ set_ist(&idt_tables[cpu][TRAP_debug], IST_NONE);
for ( stub_page = 0, i = cpu & ~(STUBS_PER_PAGE - 1);
i < nr_cpu_ids && i <= (cpu | (STUBS_PER_PAGE - 1)); ++i )
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 1060d7606c..3f046def51 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -259,13 +259,13 @@ static void show_guest_stack(struct vcpu *v, const struct
cpu_user_regs *regs)
/*
* Notes for get_stack_trace_bottom() and get_stack_dump_bottom()
*
- * Stack pages 0, 1 and 2:
+ * Stack pages 0 - 3:
* These are all 1-page IST stacks. Each of these stacks have an exception
* frame and saved register state at the top. The interesting bound for a
* trace is the word adjacent to this, while the bound for a dump is the
* very top, including the exception frame.
*
- * Stack pages 3, 4 and 5:
+ * Stack pages 4 and 5:
* None of these are particularly interesting. With MEMORY_GUARD, page 5 is
* explicitly not present, so attempting to dump or trace it is
* counterproductive. Without MEMORY_GUARD, it is possible for a call chain
@@ -286,12 +286,12 @@ unsigned long get_stack_trace_bottom(unsigned long sp)
{
switch ( get_stack_page(sp) )
{
- case 0 ... 2:
+ case 0 ... 3:
return ROUNDUP(sp, PAGE_SIZE) -
offsetof(struct cpu_user_regs, es) - sizeof(unsigned long);
#ifndef MEMORY_GUARD
- case 3 ... 5:
+ case 4 ... 5:
#endif
case 6 ... 7:
return ROUNDUP(sp, STACK_SIZE) -
@@ -306,11 +306,11 @@ unsigned long get_stack_dump_bottom(unsigned long sp)
{
switch ( get_stack_page(sp) )
{
- case 0 ... 2:
+ case 0 ... 3:
return ROUNDUP(sp, PAGE_SIZE) - sizeof(unsigned long);
#ifndef MEMORY_GUARD
- case 3 ... 5:
+ case 4 ... 5:
#endif
case 6 ... 7:
return ROUNDUP(sp, STACK_SIZE) - sizeof(unsigned long);
@@ -3947,6 +3947,7 @@ void __init init_idt_traps(void)
set_ist(&idt_table[TRAP_double_fault], IST_DF);
set_ist(&idt_table[TRAP_nmi], IST_NMI);
set_ist(&idt_table[TRAP_machine_check], IST_MCE);
+ set_ist(&idt_table[TRAP_debug], IST_DB);
/* CPU0 uses the master IDT. */
idt_tables[0] = idt_table;
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index 2dfc08f52b..964f3121b9 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -736,7 +736,7 @@ ENTRY(device_not_available)
ENTRY(debug)
pushq $0
movl $TRAP_debug,4(%rsp)
- jmp handle_exception
+ jmp handle_ist_exception
ENTRY(int3)
pushq $0
diff --git a/xen/include/asm-x86/processor.h b/xen/include/asm-x86/processor.h
index 0291e82de3..bcf647cbcc 100644
--- a/xen/include/asm-x86/processor.h
+++ b/xen/include/asm-x86/processor.h
@@ -447,7 +447,8 @@ struct __packed __cacheline_aligned tss_struct {
#define IST_DF 1UL
#define IST_NMI 2UL
#define IST_MCE 3UL
-#define IST_MAX 3UL
+#define IST_DB 4UL
+#define IST_MAX 4UL
/* Set the interrupt stack table used by a particular interrupt
* descriptor table entry. */
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.9
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