From: G. David Butler gdb@dbSystems.com
Subject: [9fans] Re: Bug in sysrendezvous?
Date: Tue, 16 Sep 1997 13:39:52 -0500 [thread overview]
Message-ID: <19970916183952.QCcp2mXHT6C0G0pzbUh25pEaWYIhWwreCXPADegJGSw@z> (raw)
From: Amos Shapir <amos@cs.huji.ac.il>
Date: Mon, 3 Jun 1996 09:59:36 -0400
>
>The "tag" operand of rendezvous is defined as ulong; but in the
>function sysrendezvous (in sysproc.c), it's copied into an int, which
>is used as an index in a table by the REND macro. If I'm mistaken
>correctly, this means that if the tag is negative, the resulting
>pointer would point *outside* the table!
>
>I guess this bug was not discovered because the tag is usually an
>address in user space, but nothing in the manual suggests it has to be
>below 0x80000000 (or that it shouldn't be 0xdeadbeef...)
>
>Did anybody else had any trouble with this?
Did you? I am now getting into the rendezvous stuff and looked back
and found your mail. Did you do anything about this? If so, what?
Perhaps just casting the value to a ulong before the hash calc will
work? All that is really needed is the remainder. (positive of course.)
change
#define REND(p,s) ((p)->rendhash[(s)%RENDHASH])
to
#define REND(p,s) ((p)->rendhash[(ulong)(s)%RENDHASH])
David Butler
gdb@dbSystems.com
next reply other threads:[~1997-09-16 18:39 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
1997-09-16 18:39 G.David [this message]
-- strict thread matches above, loose matches on Subject: below --
1997-09-16 19:00 G.David
1997-09-16 16:39 forsyth
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