linux-kernel - /proc/timer_list and weird behavior with dropbear

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 19 Jul 2013 17:28:00 +0200
From:	Holger Hans Peter Freyther <holger@...yther.de>
To:	Nathan Zimmer <nzimmer@....com>
Cc:	linux-kernel@...r.kernel.org
Subject: /proc/timer_list and weird behavior with dropbear

Dear Nathan,

I am currently upgrading a kernel for a TI Davinci DM644x based design
from Linux 3.2 to Linux 3.10.1. I have a funny re-producible issue that
goes away by reverting b3956a896ea57f25cacd74708b8fab611543a81d.

The dropbear sshd will open several files after accepting a connection to
generate some entropy. The "/proc/timer_list" file is part of that[1].
It will open that file and will try to read until the end of the file, but
most of the time this end never comes. According to strace the read on the
fd will always return 2048. I have attached the testcase I am using to
re-produce the issue.

Can this be re-produced by anyone else?

holger

[1] https://secure.ucc.asn.au/hg/dropbear/file/028fa77f952f/random.c#l204

View attachment "proc_test.c" of type "text/x-csrc" (723 bytes)