[PATCH] linux: Clear mode_t padding bits (BZ#25623)

[Florian Weimer]

* Adhemerval Zanella:

> diff --git a/sysdeps/unix/sysv/linux/msgctl.c b/sysdeps/unix/sysv/linux/msgctl.c
> index 27879e76cd..48801a3fba 100644
> --- a/sysdeps/unix/sysv/linux/msgctl.c
> +++ b/sysdeps/unix/sysv/linux/msgctl.c

> +#else
> +	  /* Old Linux kernel versions might not clear the mode padding.  */
> +	  if (sizeof ((struct msqid_ds){0}.msg_perm.mode
> +	      != sizeof ((struct __old_ipc_perm){0}.mode)))
> +	    buf->msg_perm.mode &= 0xFFFF;
> +#endif

The condition always evaluates to true becaduse the first sizeof is
applied to the result of the != operator.

Thanks,
Florian