diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2021-09-15 17:12:59 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-09-21 13:57:43 +0200 |
| commit | 44b979fa302cab91bdd2cc982823e5c13202cd4e (patch) | |
| tree | 95cda92efb3adb9b44d233dbd979e3ecfd9fa66e /arch/x86/kernel/traps.c | |
| parent | b968e84b509da593c50dc3db679e1d33de701f78 (diff) | |
x86/mm/64: Improve stack overflow warnings
Current code has an explicit check for hitting the task stack guard;
but overflowing any of the other stacks will get you a non-descript
general #DF warning.
Improve matters by using get_stack_info_noinstr() to detetrmine if and
which stack guard page got hit, enabling a better stack warning.
In specific, Michael Wang reported what turned out to be an NMI
exception stack overflow, which is now clearly reported as such:
[] BUG: NMI stack guard page was hit at 0000000085fd977b (stack is 000000003a55b09e..00000000d8cce1a5)
Reported-by: Michael Wang <yun.wang@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Wang <yun.wang@linux.alibaba.com>
Link: https://lkml.kernel.org/r/YUTE/NuqnaWbST8n@hirez.programming.kicks-ass.net
Diffstat (limited to 'arch/x86/kernel/traps.c')
| -rw-r--r-- | arch/x86/kernel/traps.c | 25 |
1 files changed, 13 insertions, 12 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index f3f3034b06f3..cc6de3a01293 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -313,17 +313,19 @@ out: } #ifdef CONFIG_VMAP_STACK -__visible void __noreturn handle_stack_overflow(const char *message, - struct pt_regs *regs, - unsigned long fault_address) +__visible void __noreturn handle_stack_overflow(struct pt_regs *regs, + unsigned long fault_address, + struct stack_info *info) { - printk(KERN_EMERG "BUG: stack guard page was hit at %p (stack is %p..%p)\n", - (void *)fault_address, current->stack, - (char *)current->stack + THREAD_SIZE - 1); - die(message, regs, 0); + const char *name = stack_type_name(info->type); + + printk(KERN_EMERG "BUG: %s stack guard page was hit at %p (stack is %p..%p)\n", + name, (void *)fault_address, info->begin, info->end); + + die("stack guard page", regs, 0); /* Be absolutely certain we don't return. */ - panic("%s", message); + panic("%s stack guard hit", name); } #endif @@ -353,6 +355,7 @@ DEFINE_IDTENTRY_DF(exc_double_fault) #ifdef CONFIG_VMAP_STACK unsigned long address = read_cr2(); + struct stack_info info; #endif #ifdef CONFIG_X86_ESPFIX64 @@ -455,10 +458,8 @@ DEFINE_IDTENTRY_DF(exc_double_fault) * stack even if the actual trigger for the double fault was * something else. */ - if ((unsigned long)task_stack_page(tsk) - 1 - address < PAGE_SIZE) { - handle_stack_overflow("kernel stack overflow (double-fault)", - regs, address); - } + if (get_stack_guard_info((void *)address, &info)) + handle_stack_overflow(regs, address, &info); #endif pr_emerg("PANIC: double fault, error_code: 0x%lx\n", error_code); |