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[Guile-commits] 02/05: Avoid signed integer overflows in numeric convers
From: |
Mark H. Weaver |
Subject: |
[Guile-commits] 02/05: Avoid signed integer overflows in numeric conversions. |
Date: |
Mon, 20 Jun 2016 19:52:09 +0000 (UTC) |
mhw pushed a commit to branch stable-2.0
in repository guile.
commit 4b60562820d001674ec7124c4a10391ecf7e44c3
Author: Mark H Weaver <address@hidden>
Date: Wed Feb 24 02:17:43 2016 -0500
Avoid signed integer overflows in numeric conversions.
Reported by Miroslav Lichvar <address@hidden>
in <https://lists.gnu.org/archive/html/guile-devel/2016-02/msg00045.html>
* libguile/conv-integer.i.c: Avoid signed overflow.
* libguile/numbers.c (scm_is_signed_integer): Avoid signed overflow.
---
libguile/conv-integer.i.c | 15 ++++++++++-----
libguile/numbers.c | 15 ++++++++++-----
2 files changed, 20 insertions(+), 10 deletions(-)
diff --git a/libguile/conv-integer.i.c b/libguile/conv-integer.i.c
index 4cf887c..fe2d363 100644
--- a/libguile/conv-integer.i.c
+++ b/libguile/conv-integer.i.c
@@ -64,25 +64,30 @@ SCM_TO_TYPE_PROTO (SCM val)
}
else
{
- scm_t_intmax n;
+ scm_t_uintmax abs_n;
+ TYPE n;
size_t count;
if (mpz_sizeinbase (SCM_I_BIG_MPZ (val), 2)
> CHAR_BIT*sizeof (scm_t_uintmax))
goto out_of_range;
- mpz_export (&n, &count, 1, sizeof (scm_t_uintmax), 0, 0,
+ mpz_export (&abs_n, &count, 1, sizeof (scm_t_uintmax), 0, 0,
SCM_I_BIG_MPZ (val));
if (mpz_sgn (SCM_I_BIG_MPZ (val)) >= 0)
{
- if (n < 0)
+ if (abs_n <= TYPE_MAX)
+ n = abs_n;
+ else
goto out_of_range;
}
else
{
- n = -n;
- if (n >= 0)
+ /* Carefully avoid signed integer overflow. */
+ if (TYPE_MIN < 0 && abs_n - 1 <= -(TYPE_MIN + 1))
+ n = -1 - (TYPE)(abs_n - 1);
+ else
goto out_of_range;
}
diff --git a/libguile/numbers.c b/libguile/numbers.c
index 1e3fc30..5aaac64 100644
--- a/libguile/numbers.c
+++ b/libguile/numbers.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1995-2015 Free Software Foundation, Inc.
+/* Copyright (C) 1995-2016 Free Software Foundation, Inc.
*
* Portions Copyright 1990, 1991, 1992, 1993 by AT&T Bell Laboratories
* and Bellcore. See scm_divide.
@@ -9622,6 +9622,7 @@ scm_is_signed_integer (SCM val, scm_t_intmax min,
scm_t_intmax max)
}
else
{
+ scm_t_uintmax abs_n;
scm_t_intmax n;
size_t count;
@@ -9629,18 +9630,22 @@ scm_is_signed_integer (SCM val, scm_t_intmax min,
scm_t_intmax max)
> CHAR_BIT*sizeof (scm_t_uintmax))
return 0;
- mpz_export (&n, &count, 1, sizeof (scm_t_uintmax), 0, 0,
+ mpz_export (&abs_n, &count, 1, sizeof (scm_t_uintmax), 0, 0,
SCM_I_BIG_MPZ (val));
if (mpz_sgn (SCM_I_BIG_MPZ (val)) >= 0)
{
- if (n < 0)
+ if (abs_n <= max)
+ n = abs_n;
+ else
return 0;
}
else
{
- n = -n;
- if (n >= 0)
+ /* Carefully avoid signed integer overflow. */
+ if (min < 0 && abs_n - 1 <= -(min + 1))
+ n = -1 - (scm_t_intmax)(abs_n - 1);
+ else
return 0;
}