diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2019-04-14 17:59:38 +0200 |
---|---|---|
committer | Borislav Petkov <bp@suse.de> | 2019-04-17 12:06:56 +0200 |
commit | 7dbcf2b0b770eeb803a416ee8dcbef78e6389d40 (patch) | |
tree | 0369eb575560c40765a4ad2dd13eb32b41b0c7ba /arch/x86/kernel/irq_64.c | |
parent | 80552f0f7aebdd8deda8ea455292cbfbf462d655 (diff) |
x86/irq/64: Limit IST stack overflow check to #DB stack
Commit
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 area 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>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
Cc: Nicolai Stange <nstange@suse.de>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190414160143.682135110@linutronix.de
Diffstat (limited to 'arch/x86/kernel/irq_64.c')
-rw-r--r-- | arch/x86/kernel/irq_64.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c index 0469cd078db1..b50ac9c7397b 100644 --- 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 interrupts + * 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(struct pt_regs *regs) 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; |