diff options
| author | Mark H Weaver <mhw@netris.org> | 2016-02-24 02:17:43 -0500 |
|---|---|---|
| committer | Andy Wingo <wingo@pobox.com> | 2017-03-01 19:05:30 +0100 |
| commit | a8d1c7d61018bb2c77c6ffd57f3c1672361ce1e9 (patch) | |
| tree | fbcf9010aa16eac83eeb7eb2597efc10125b99fd /libguile | |
| parent | 36321a8ffd95c8a73bd63dd6ab9fdd81590b7558 (diff) | |
Avoid signed integer overflows in numeric conversions.
Reported by Miroslav Lichvar <mlichvar@redhat.com>
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.
Diffstat (limited to 'libguile')
| -rw-r--r-- | libguile/conv-integer.i.c | 15 | ||||
| -rw-r--r-- | 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 a5362d39c..0aa81dc74 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 0d053c867..34980c6a9 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. @@ -9641,6 +9641,7 @@ 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; @@ -9648,18 +9649,22 @@ 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; } |