Re: [uml-devel] current_thread_info() returns invalid pointer in early UML boot code

[Vegard N. <veg...@gm...>]

On 21 May 2016 at 20:18, Thomas Meyer <th...@m3...> wrote:
> Am 21.05.2016 um 15:51 schrieb Vegard Nossum <veg...@gm...>:
>> I'm having some trouble with using current_thread_info() during UML
>> early boot. Sometimes it works just fine, but often I get segfaults
>> because current_thread_info() is returning an invalid pointer. It
>> looks random: 0x202118, 0x1003e0003, 0xd33b90b3, 0x6db043, etc.
>
> Mhh. Strange. Do you have a stack trace to call to current thread info which ends up with a wrong value. I wonder from were it originates.

One such trace would be:

#2  0x000000006026652c in snprintf (buf=<optimized out>,
size=<optimized out>, fmt=<optimized out>) at lib/vsprintf.c:2181
#3  0x00000000600046f8 in setup_env_path () at arch/um/os-Linux/main.c:109
#4  main (argc=3, argv=0x7ffc3d8c23e8, envp=<optimized out>) at
arch/um/os-Linux/main.c:125

I wonder why setup_env_path() ends up calling the kernel's snprintf(),
I thought that it would be using the glibc snprintf() at this point?


Vegard