[PATCH] arm64: fix for bad_mode() handler to always result in panic

[f.fainelli@gmail.com (Florian Fainelli)]

On 08/08/2018 11:18 AM, Hari Vyas wrote:
> On Tue, Aug 7, 2018 at 5:57 PM, Greg KH <greg@kroah.com> wrote:
>> On Tue, Aug 07, 2018 at 04:33:48PM +0530, Hari Vyas wrote:
>>> bad_mode() handler is called for invalid or undefined
>>> instruction in el1 level or when irq,fiq,sync or error
>>> situation happen in el1 or el0 level.
>>>
>>> As per latest code, above abnormal situation may not result in
>>> panic always due to die() call if user mode is determined at
>>> that moment. That will just result in kill of current process
>>> and panic will be avoided which it must not.
>>>
>>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=200637
>>> Signed-off-by: Hari Vyas <hari.vyas@broadcom.com>
>>> ---
>>>  arch/arm64/kernel/traps.c | 1 -
>>>  1 file changed, 1 deletion(-)
>>>
>>> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
>>> index d399d45..716ee73 100644
>>> --- a/arch/arm64/kernel/traps.c
>>> +++ b/arch/arm64/kernel/traps.c
>>> @@ -621,7 +621,6 @@ asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
>>>               handler[reason], smp_processor_id(), esr,
>>>               esr_get_class_string(esr));
>>>
>>> -     die("Oops - bad mode", regs, 0);
>>>       local_daif_mask();
>>>       panic("bad mode");
>>>  }
>>> --
>>> 1.9.1
>>
>> <formletter>
>>
>> This is not the correct way to submit patches for inclusion in the
>> stable kernel tree.  Please read:
>>     https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
>> for how to do this properly.
>>
>> </formletter>
> 
> Thanks. Probably my mistake to include stable kernel list for regular
> minor patch.
> In any case, will take care about it along with arm maintainers and
> developers review comments which I am awaiting.

Also, if this is a real fix, then providing an appropriate Fixes: tag
would help understand when this broke, and how far back this needs to be
backported to. This of course, assumes that your patch is the right
course of action.
-- 
Florian