Re: [tytso-DPNOqEs/LNQ@public.gmane.org: [PATCH, RFC -v3] random: introduce getrandom(2) system call]

On Fri, Jul 18, 2014 at 03:16:18PM +0200, Arnd Bergmann wrote:

On Friday 18 July 2014 08:56:06 Theodore Ts'o wrote:

quoted

The change in the v3 version of the commit was to eliminate potential
short reads and EINTR returns when reading from urandom (once the
urandom pool is initialized).  This was based on comments and requests
from Theo de Raadt.  See the NOTES section in the suggested man page for
a more in-depth discussion of the issues involved.

I think there is a problem with the completion...

However, here you can get called an arbitrary number of times.
It seems entirely possible than an attacker can manage to call
this function 2 billion times. Assuming a latency of 1 microsecond
per syscall, that would take about half an hour. After that, you
never again get any urandom data out of the syscall.

I think you are better off using a plain wait_event() here.

Nice catch, thanks!!

I'll rework the patch to use wait_event().

							- Ted