[PATCH 2/2] arm64: mm: don't print out page table entries on EL0 faults

[Kristina Martsenko]

On 22/05/17 13:21, Will Deacon wrote:
> On Mon, May 22, 2017 at 12:45:54PM +0100, Kristina Martsenko wrote:
>> When we take a fault from EL0 that can't be handled, we print out the
>> page table entries associated with the faulting address. This allows
>> userspace to print out any current page table entries, including kernel
>> (TTBR1) entries.  Exposing kernel mappings like this could pose a
>> security risk, so don't print out page table information on EL0 faults.
>> (But still print it out for EL1 faults.)
>>
>> Signed-off-by: Kristina Martsenko <kristina.martsenko at arm.com>
> 
> It might be worth mentioning that this follows the same behaviour as x86.

Yep.

> In fact, they print the name of the faulting VMA using print_vma_addr,
> which might be useful too.

Looks useful, should I add that in a separate patch in v2?

Thanks,
Kristina

>> ---
>>  arch/arm64/mm/fault.c | 1 -
>>  1 file changed, 1 deletion(-)
>>
>> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
>> index 0c32f34fb4af..798841f4b00a 100644
>> --- a/arch/arm64/mm/fault.c
>> +++ b/arch/arm64/mm/fault.c
>> @@ -260,7 +260,6 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
>>  		pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",
>>  			tsk->comm, task_pid_nr(tsk), inf->name, sig,
>>  			addr, esr);
>> -		show_pte(addr);
>>  		show_regs(regs);
>>  	}
>>  
>> -- 
>> 2.1.4
>>