From: Andrey Utkin <andrey.krieger.utkin@gmail.com>
To: tytso@mit.edu, hannes@stressinduktion.org
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Reading large amounts from /dev/urandom broken
Date: Wed, 23 Jul 2014 16:52:21 +0300 [thread overview]
Message-ID: <CANZNk81nyws__swPUoxz912wi5PJ2CBXbiLpJ-Jc4oLcX+J8vw@mail.gmail.com> (raw)
Dear developers, please check bugzilla ticket
https://bugzilla.kernel.org/show_bug.cgi?id=80981 (not the initial
issue, but starting with comment#3.
Reading from /dev/urandom gives EOF after 33554431 bytes. I believe
it is introduced by commit 79a8468747c5f95ed3d5ce8376a3e82e0c5857fc,
with the chunk
nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
which is described in commit message as "additional paranoia check to
prevent overly large count values to be passed into urandom_read()".
I don't know why people pull such large amounts of data from urandom,
but given today there are two bugreports regarding problems doing
that, i consider that this is practiced.
--
Andrey Utkin
next reply other threads:[~2014-07-23 13:52 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-23 13:52 Andrey Utkin [this message]
2014-07-23 14:32 ` Reading large amounts from /dev/urandom broken Hannes Frederic Sowa
2014-07-23 15:14 ` Theodore Ts'o
2014-07-23 15:19 ` Hannes Frederic Sowa
2014-07-24 20:39 ` Alex Elsayed
2014-08-09 7:45 ` Pavel Machek
2014-08-10 11:51 ` Andrey Utkin
2014-08-12 9:14 ` Pavel Machek
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