[PATCH] IOMUX: Fix access past end of console_devices

[Sean Anderson]

On 3/30/22 1:01 PM, Andy Shevchenko wrote:
> On Wed, Mar 30, 2022 at 7:49 PM Sean Anderson <seanga2 at gmail.com> wrote:
>>
>> We should only access console_devices[file][i] once we have checked that
>> i < cd_count[file]. Otherwise, we will access uninitialized memory at the end of
>> the loop. console_devices[file][i] should not be NULL, but putting the
>> assignment in the loop condition allows us to ensure that i is checked
>> beforehand. This isn't a bug, but it does make valgrind stop complaining.
> 
>> Fixes: 400797cad3 ("IOMUX: Split out for_each_console_dev() helper macro")
> 
> Has this been tested? See below.

Yes.

> ...
> 
>>   #define for_each_console_dev(i, file, dev)             \
>> -       for (i = 0, dev = console_devices[file][i];     \
> 
> When we enter the loop, the dev is assigned and perhaps valid
> 
>> -            i < cd_count[file];                        \
>> -            i++, dev = console_devices[file][i])
>> +       for (i = 0; i < cd_count[file] &&               \
> 
> Not the case anymore.

The loop condition is evaluated before we enter the loop,
which includes the first assignment to dev.

--Sean

>> +               (dev = console_devices[file][i]); i++)
> 
> 
>