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Date:      Fri, 10 Apr 1998 21:33:27 +0200
From:      Wolfram Schneider <wosch@cs.tu-berlin.de>
To:        ak@muc.de
Cc:        freebsd-fs@FreeBSD.ORG
Subject:   Re: cvs commit: src/sbin/mount mntopts.h mount.8 mount.c src/sys/kern          vfs_lookup.c vfs_syscalls.c vfs_vnops.c src/sys/sys mount.h
Message-ID:  <19980410213327.22843@panke.de>
In-Reply-To: <19980410171454.39443@fred.muc.de>; from ak@muc.de on Fri, Apr 10, 1998 at 05:14:54PM %2B0200
References:  <199804081832.LAA04184@freefall.freebsd.org> <k2emz5oqe9.fsf@zero.aec.at> <19980410164505.27668@panke.de> <19980410171454.39443@fred.muc.de>

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On 1998-04-10 17:14:54 +0200, ak@muc.de wrote:
> > I can add a nonamedpipe option ;-)
> Or include that with nodev (or does it do that already?)

nodev don't disable named pipes.


> > A named pipe race is much harder to implement than a symlink race.
> > How do you avoid dead locks?
> What deadlocks? the exploit will be "single threaded" but I don't think
> there are deadlocks. It is possible, that is what counts. 

Possible dead lock:

A writes 2K into the named pipe
B append 8K into the named pipe
A read 2K from the named pipe

A want write 2K into the named pipe, but B not finished writing.
A wait for B and B wait for A ....

> Just use O_CREAT|O_EXCL always.

-- 
Wolfram Schneider   <wosch@freebsd.org>   http://www.freebsd.org/~wosch/

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