Re: [PATCH v2] lib/test_printf.c: call wait_for_random_bytes() before plain %p tests

[Andy Shevchenko]

On Wed, Jun 13, 2018 at 5:59 PM, Thierry Escande
<thierry.escande@xxxxxxxxxx> wrote:
> On 13/06/2018 13:22, Andy Shevchenko wrote:
>>
>> On Wed, Jun 13, 2018 at 12:29 PM, Thierry Escande
>> <thierry.escande@xxxxxxxxxx> wrote:
>>>
>>> If the test_printf module is loaded before the crng is initialized, the
>>> plain 'p' tests will fail because the printed address will not be hashed
>>> and the buffer will contain "(ptrval)" instead.
>>> Since we cannot wait for the crng to be initialized for an undefined
>>> time, both plain 'p' tests now accept the string "(ptrval)" as a valid
>>> result and print a warning message.
>>
>>
>> There are two possibilities:
>>   1. (ptrval) for 32-bit case
>>   2. (____ptrval____) for 64-bit case.
>
>
> From lib/vsprintf.c, ptr_to_id() puts "(ptrval)" into the buffer, then it
> gets left-padded with spaces by widen_string().

Which kernel version you are trying to fix?

What I see for a long time in linux-next:

static char *ptr_to_id(char *buf, char *end, void *ptr, struct printf_spec spec)
{
        const char *str = sizeof(ptr) == 8 ? "(____ptrval____)" : "(ptrval)";
...

brought by the commit 91efafb1dd8f ("lib/vsprintf: Replace space with
'_' before crng is ready").

-- 
With Best Regards,
Andy Shevchenko