Date: Thu, 5 Apr 2001 17:56:12 -0700 (PDT) From: Matt Dillon <dillon@earth.backplane.com> To: Brian Somers <brian@Awfulhak.org> Cc: "Andrey A. Chernov" <ache@nagual.pp.ru>, Mark.Andrews@nominum.com, Chris Byrnes <chris@jeah.net>, security@FreeBSD.ORG, brian@Awfulhak.org Subject: Re: ntpd patch Message-ID: <200104060056.f360uCN35967@earth.backplane.com> References: <200104060033.f360XfP03505@hak.lan.Awfulhak.org>
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The issue here is that 'tp' is a 'char' type, which may be signed
by default (e.g. on IA32 it is signed). If you pass a signed char
to a ctype macro/function taking an int, any character >= 0x80 will be
turned into a negative number when it is expanded to an integer.
The cast to unsigned char simply ensures that when the character is
expanded to an integer in the procedure call, it is not converted
into a negative number.
Now, I don't think FreeBSD cares about this at all. However, many
older systems do care and it is just plain common sense to not pass
a negative number to a ctype macro when you don't need to. The last
time I had to port a piece of software to a Solaris box (I don't remember
what version it was running), with -Wall -Wstrict-prototypes, the
solaris box complained mightily about passing a char to a ctype macro.
This is just common sense, really. How generic do we want the code
to be? It certainly doesn't hurt.
-Matt
:>
:> + while (tp != buf && isspace((unsigned char)(*(tp-1))))
:>
:> (int) cast is completely wrong and dangerous.
:
:$ man isspace
:.....
:SYNOPSIS
: #include <ctype.h>
:
: int
: isspace(int c)
:.....
:
:I believe the int is correct.
:
:> --
:> Andrey A. Chernov
:> http://ache.pp.ru/
:
:--
:Brian <brian@Awfulhak.org> <brian@[uk.]FreeBSD.org>
: <http://www.Awfulhak.org>; <brian@[uk.]OpenBSD.org>
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