From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
Subject: [patch 01/14] x86/irq/64: Limit IST stack overflow check to #DB stack
Date: Sun, 31 Mar 2019 23:40:21 +0200 [thread overview]
Message-ID: <20190331215134.837052834@linutronix.de> (raw)
In-Reply-To: 20190331214020.836098943@linutronix.de
37fe6a42b343 ("x86: Check stack overflow in detail") added a broad check
for the full exception stack area, i.e. it considers the full exception
stack are as valid.
That's wrong in two aspects:
1) It does not check the individual areas one by one
2) #DF, NMI and #MCE are not enabling interrupts which means that a
regular device interrupt cannot happen in their context. In fact if a
device interrupt hits one of those IST stacks that's a bug because some
code path enabled interrupts while handling the exception.
Limit the check to the #DB stack and consider all other IST stacks as
'overflow' or invalid.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
---
arch/x86/kernel/irq_64.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -26,9 +26,18 @@ int sysctl_panic_on_stackoverflow;
/*
* Probabilistic stack overflow check:
*
- * Only check the stack in process context, because everything else
- * runs on the big interrupt stacks. Checking reliably is too expensive,
- * so we just check from interrupts.
+ * Regular device interrupts can enter on the following stacks:
+ *
+ * - User stack
+ *
+ * - Kernel task stack
+ *
+ * - Interrupt stack if a device driver reenables interrupt
+ * which should only happen in really old drivers.
+ *
+ * - Debug IST stack
+ *
+ * All other contexts are invalid.
*/
static inline void stack_overflow_check(struct pt_regs *regs)
{
@@ -53,8 +62,8 @@ static inline void stack_overflow_check(
return;
oist = this_cpu_ptr(&orig_ist);
- estack_top = (u64)oist->ist[0] - EXCEPTION_STKSZ + STACK_TOP_MARGIN;
- estack_bottom = (u64)oist->ist[N_EXCEPTION_STACKS - 1];
+ estack_bottom = (u64)oist->ist[DEBUG_STACK];
+ estack_top = estack_bottom - DEBUG_STKSZ + STACK_TOP_MARGIN;
if (regs->sp >= estack_top && regs->sp <= estack_bottom)
return;
next prev parent reply other threads:[~2019-03-31 22:11 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-31 21:40 [patch 00/14] x86/exceptions: Add guard patches to IST stacks Thomas Gleixner
2019-03-31 21:40 ` Thomas Gleixner [this message]
2019-04-01 18:03 ` [patch 01/14] x86/irq/64: Limit IST stack overflow check to #DB stack Borislav Petkov
2019-04-02 16:34 ` Sean Christopherson
2019-03-31 21:40 ` [patch 02/14] x86/idt: Remove unused macro SISTG Thomas Gleixner
2019-04-01 4:04 ` Andy Lutomirski
2019-03-31 21:40 ` [patch 03/14] x86/exceptions: Remove unused stack defines on 32bit Thomas Gleixner
2019-03-31 21:40 ` [patch 04/14] x86/exceptions: Make IST index zero based Thomas Gleixner
2019-04-01 7:30 ` Peter Zijlstra
2019-04-01 7:33 ` Thomas Gleixner
2019-04-02 16:49 ` Sean Christopherson
2019-04-03 16:35 ` Borislav Petkov
2019-03-31 21:40 ` [patch 05/14] x86/cpu_entry_area: Cleanup setup functions Thomas Gleixner
2019-03-31 21:40 ` [patch 06/14] x86/exceptions: Add structs for exception stacks Thomas Gleixner
2019-03-31 21:40 ` [patch 07/14] x86/cpu_entry_area: Prepare for IST guard pages Thomas Gleixner
2019-03-31 21:40 ` [patch 08/14] x86/cpu_entry_area: Provide exception stack accessor Thomas Gleixner
2019-03-31 21:40 ` [patch 09/14] x86/traps: Use cpu_entry_area instead of orig_ist Thomas Gleixner
2019-03-31 21:40 ` [patch 10/14] x86/irq/64: Use cpu entry area " Thomas Gleixner
2019-03-31 21:40 ` [patch 11/14] x86/dumpstack/64: Use cpu_entry_area " Thomas Gleixner
2019-03-31 21:40 ` [patch 12/14] x86/cpu: Prepare TSS.IST setup for guard pages Thomas Gleixner
2019-04-02 16:57 ` Sean Christopherson
2019-03-31 21:40 ` [patch 13/14] x86/cpu: Remove orig_ist array Thomas Gleixner
2019-03-31 21:40 ` [patch 14/14] x86/exceptions: Enable IST guard pages Thomas Gleixner
2019-04-02 10:19 ` [patch 15/14] x86/dumpstack/64: Speedup in_exception_stack() Thomas Gleixner
2019-04-02 15:43 ` Josh Poimboeuf
2019-04-02 15:48 ` Thomas Gleixner
2019-04-02 15:51 ` Josh Poimboeuf
2019-04-02 15:53 ` Josh Poimboeuf
2019-04-03 8:08 ` Peter Zijlstra
2019-04-03 8:10 ` Peter Zijlstra
2019-04-03 15:11 ` Josh Poimboeuf
2019-04-02 16:11 ` Andy Lutomirski
2019-04-02 18:27 ` Thomas Gleixner
2019-04-02 19:29 ` Thomas Gleixner
2019-04-03 0:36 ` Andy Lutomirski
2019-04-03 16:26 ` Thomas Gleixner
2019-04-03 19:42 ` Thomas Gleixner
2019-04-04 0:03 ` Andy Lutomirski
2019-04-02 19:02 ` Rasmus Villemoes
2019-04-02 19:21 ` Thomas Gleixner
2019-04-03 8:02 ` Peter Zijlstra
2019-04-01 4:03 ` [patch 00/14] x86/exceptions: Add guard patches to IST stacks Andy Lutomirski
2019-04-03 16:30 ` Thomas Gleixner
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