--- Begin Message ---
Subject: |
floating point exception on invalid argument |
Date: |
Mon, 27 Oct 2014 21:06:01 +0100 |
User-agent: |
Mutt/1.5.22 (2013-10-16) |
Hi,
on 64 bit systems, an invalid tabsize argument can trigger a floating
point exception:
$ diff --tabsize=9223372036854775808 . .
Floating point exception
Offending line is this one:
intmax_t off = (w + t + GUTTER_WIDTH_MINIMUM) / (2 * t) * t;
The tabsize I supplied is 2^63, multiplying by 2 will be 2^64 which
is too large, so the divisor overflows to 0.
This is a purely cosmetical fix, I don't see the need to adjust anything
except avoiding this special value. I doubt that anyone ever needed
these large numbers.
Tobias
--- diffutils-3.3/src/diff.c~ 2014-10-27 20:54:30.968656876 +0100
+++ diffutils-3.3/src/diff.c 2014-10-27 20:54:41.360708407 +0100
@@ -594,7 +594,7 @@
case TABSIZE_OPTION:
numval = strtoumax (optarg, &numend, 10);
- if (! (0 < numval && numval <= SIZE_MAX) || *numend)
+ if (! (0 < numval && numval <= SIZE_MAX / 2) || *numend)
try_help ("invalid tabsize '%s'", optarg);
if (tabsize != numval)
{
--- End Message ---
--- Begin Message ---
Subject: |
Re: [bug-diffutils] bug#18857: floating point exception on invalid argument |
Date: |
Mon, 27 Oct 2014 22:24:48 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 |
Tobias Stoeckmann wrote:
I don't see the need to adjust anything
except avoiding this special value. I doubt that anyone ever needed
these large numbers.
Yes, it's hard to imagine anyone needing a tabsize that large. Still, the GNU
policy is to avoid unnecessary limits, so it's better to make the limit as large
as easily possible, which here would be SIZE_MAX - GUTTER_WIDTH_MINIMUM. Also,
I see there are other ways the nearby code can overflow. Plus, we should put in
a test case for this bug. So I installed the attached patch, which should
address these issues. Thanks for reporting the problem.
0001-diff-fix-integer-overflow-problem-with-tabsize.patch
Description: Text document
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