From: random832@fastmail.com (Random832)
Subject: [TUHS] The evolution of Unix facilities and architecture
Date: Fri, 12 May 2017 19:52:49 -0400 [thread overview]
Message-ID: <1494633169.1599957.975050752.2FB9B2DA@webmail.messagingengine.com> (raw)
In-Reply-To: <alpine.BSF.2.20.1705130937330.67621@aneurin.horsfall.org>
On Fri, May 12, 2017, at 19:38, Dave Horsfall wrote:
> On Fri, 12 May 2017, Noel Chiappa wrote:
>
> > So when we got back from dinner, I looked at the source to our system to see
> > if I was right, and.... it had already been fixed! Here's the code:
> >
> > if (xp->x_count!=1 || xp->x_iptr->i_mode&ISVTX)
> > goto error;
>
> Err, isn't that the sticky bit, not the setuid bit?
The sticky bit makes it keep the image in memory when there are no
processes using it. I assume x_count is determining whether there are
processes using it. So, taken together, these checks are "is there or
might there be in the future a process, other than the one being
debugged, using this exact copy of the image rather than loading it from
the disk".
The next line is "xp->x_iptr->i_flag &= ~ITEXT", which I assume prevents
the image from being reused for other processes started while this one
is running.
I am looking at 7th edition in the UnixTree site, the whole fix is:
/*
* If text, must assure exclusive use
*/
if (xp = u.u_procp->p_textp) {
if (xp->x_count!=1 || xp->x_iptr->i_mode&ISVTX)
goto error;
xp->x_iptr->i_flag &= ~ITEXT;
}
The equivalent section to the one this appears in in 6th edition doesn't
have the fix, and the comment claims, doesn't work at all:
/* write user I (for now, always an error) */
case 4:
if (suiword(ipc.ip_addr, 0) < 0)
goto error;
suiword(ipc.ip_addr, ipc.ip_data);
break;
This is clearly PDP-11 specific, maybe a similar bug reappeared with
demand-paged virtual memory.
next prev parent reply other threads:[~2017-05-12 23:52 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-12 23:30 Noel Chiappa
2017-05-12 23:38 ` Dave Horsfall
2017-05-12 23:52 ` Random832 [this message]
2017-05-13 0:26 ` Dave Horsfall
2017-05-13 0:48 ` Random832
2017-05-13 0:22 ` Clem Cole
2017-05-13 0:23 ` Clem Cole
[not found] <mailman.1.1494986402.2329.tuhs@minnie.tuhs.org>
2017-05-19 14:31 ` David
-- strict thread matches above, loose matches on Subject: below --
2017-05-16 13:20 Noel Chiappa
2017-05-16 13:46 ` Clem Cole
2017-05-14 21:44 Noel Chiappa
2017-05-13 1:25 Noel Chiappa
2017-05-13 0:44 Noel Chiappa
2017-05-13 0:51 ` Random832
2017-05-13 0:55 ` Dave Horsfall
2017-05-13 1:17 ` Chris Torek
2017-05-13 15:25 ` Steve Simon
2017-05-13 16:55 ` Clem Cole
2017-05-13 17:19 ` William Pechter
2017-05-14 12:55 ` Derek Fawcus
2017-05-14 22:12 ` Dave Horsfall
2017-05-15 1:24 ` Nemo
2017-05-15 18:00 ` Steve Johnson
2017-05-16 22:33 ` Ron Natalie
2017-05-16 23:13 ` Arthur Krewat
2017-05-16 23:18 ` Ron Natalie
2017-05-13 23:01 ` Dave Horsfall
2017-05-12 18:43 Doug McIlroy
2017-05-12 18:56 ` Dan Cross
2017-05-12 19:43 ` Clem Cole
2017-05-12 20:06 ` Clem Cole
2017-05-12 20:40 ` Jeremy C. Reed
2017-05-12 21:29 ` Clem Cole
2017-05-12 21:29 ` Ron Natalie
2017-05-12 15:12 Noel Chiappa
2017-05-12 15:17 ` Clem Cole
2017-05-12 15:18 ` Clem Cole
2017-05-12 15:46 ` Clem Cole
2017-05-11 17:08 Noel Chiappa
2017-05-11 21:34 ` Dave Horsfall
2017-05-11 14:07 Noel Chiappa
2017-05-11 14:21 ` Larry McVoy
2017-05-11 16:17 ` Clem Cole
2017-05-11 17:11 ` Michael Kjörling
2017-05-11 21:44 ` Dave Horsfall
2017-05-11 22:06 ` Warner Losh
2017-05-12 6:24 ` Hellwig Geisse
2017-05-12 21:12 ` Dave Horsfall
2017-05-12 23:25 ` Hellwig Geisse
2017-05-11 16:15 ` Clem Cole
2017-05-11 16:52 ` Warner Losh
2017-05-11 17:12 ` Clem Cole
2017-05-11 20:37 ` Ron Natalie
2017-05-11 22:25 ` Larry McVoy
2017-05-11 22:30 ` Ron Natalie
2017-05-11 23:47 ` Dave Horsfall
2017-05-11 23:48 ` Ron Natalie
2017-05-12 0:21 ` Larry McVoy
2017-05-12 2:42 ` Warner Losh
2017-05-12 0:16 ` Larry McVoy
2017-05-12 1:41 ` Wesley Parish
2017-05-12 1:05 ` Toby Thain
2017-05-12 8:17 ` Michael Kjörling
2017-05-12 13:56 ` Tim Bradshaw
2017-05-12 14:22 ` Michael Kjörling
2017-05-12 14:30 ` Larry McVoy
2017-05-12 15:11 ` Tim Bradshaw
2017-05-12 15:52 ` Chet Ramey
2017-05-12 16:21 ` Warner Losh
2017-05-12 8:15 ` Harald Arnesen
2017-05-14 4:30 ` Theodore Ts'o
2017-05-14 17:40 ` Clem Cole
2017-05-10 14:08 Diomidis Spinellis
2017-05-10 14:38 ` Steffen Nurpmeso
2017-05-10 23:09 ` Erik Berls
2017-05-11 12:40 ` Steffen Nurpmeso
2017-05-11 0:49 ` Clem Cole
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