oss-sec mailing list archives

CVE request: kernel overestimates the available entropy in random pools


From: Wade Mealing <wmealing () redhat com>
Date: Mon, 27 Apr 2015 22:02:10 -0400 (EDT)

Gday All,

I'm chasing up a CVE number for an issue that was discovered/brought to
light by H. Peter Anvin, on LKML ( see https://lkml.org/lkml/2013/4/24/5 )

To quote:

"When we write entropy into a non-empty pool, we currently don't
account at all for the fact that we will probabilistically overwrite
some of the entropy in that pool.  This means that unless the pool is
fully empty, we are currently *guaranteed* to overestimate the amount
of entropy in the pool!"

The impact of this issue could be to a downgrade the kernels true
RNG to a pseudo-RNG. 

Thanks,

Wade Mealing
Red Hat Product Security


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