NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/comp/os/linux/16907

Internet Message Format | 1992-11-17 | 1.6 KB

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From: [e-mail] (Johan Myreen)
Newsgroups: comp.os.linux
Subject: Re: ANNOUNCE: Linux 0.98 pl5
Message-ID: <[e-mail]>
Date: 16 Nov 92 19:35:59 GMT
References: <[e-mail]>
Sender: [e-mail] (Usenet pseudouser id)
Organization: Helsinki University of Technology, Finland
Lines: 24
In-Reply-To: [e-mail]'s message of 15 Nov 92 22:01:38 GMT
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In article <[e-mail]> [e-mail] (Linus Torvalds) writes:

>NOTE! READ THIS AND PONDER:

>pl5 now checks against writing to the text segment.  Older binaries
>which used the original estdio library (used with the earliest gcc
>versions) are liable to break: not that there should be many of these
>binaries around.  So if you get "Segmentation fault (core dumped)" on
>binaries you know used to work, this is the likely cause.

Before the "bug reports" start coming in, I'd like to point out one
consequence of write-protected text segments. Gcc puts strings in the
text segment, and is entitled to do so, since the C standard says
string literals are const.

This breaks code modifying string literals, like for instance the
mktemp library function when called like this: mktemp("/tmp/fooXXXXXX").

This is not a bug in Linux or Gcc, but in *your* application, if you
use mktemp like this, or do tricks like "bar"[2]++...

--
Johan Myreen
[e-mail]