From be75e1713caa7b66aedc837a226091f78dfcb8fe Mon Sep 17 00:00:00 2001 From: Mark H Weaver Date: Wed, 24 Feb 2016 02:17:43 -0500 Subject: [PATCH] Avoid signed integer overflows in numeric conversions. * 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; } -- 2.6.3