From dc06b7b7156e0b1e32f32acf0b89925fd1c4b79f Mon Sep 17 00:00:00 2001 From: matz Date: Fri, 7 Jan 2011 00:17:06 +0000 Subject: [PATCH] * bignum.c (bigmul1_karatsuba): avoid overflow that make assertion fail in certain case. this patch is contributed from Ray Chason in personal communication. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@30483 b2dd03c8-39d4-4d8f-98ff-823fe69b080e --- ChangeLog | 6 ++++++ bignum.c | 12 ++++++------ 2 files changed, 12 insertions(+), 6 deletions(-) diff --git a/ChangeLog b/ChangeLog index 4ea901ce2d..644d67dd97 100644 --- a/ChangeLog +++ b/ChangeLog @@ -2,6 +2,12 @@ Fri Jan 7 00:37:35 2011 Tanaka Akira * string.c: parenthesize macro arguments. +Thu Jan 6 22:42:02 2011 Yukihiro Matsumoto + + * bignum.c (bigmul1_karatsuba): avoid overflow that make assertion + fail in certain case. this patch is contributed from Ray Chason + in personal communication. + Thu Jan 6 20:55:49 2011 NAKAMURA Usaku * lib/mkmf.rb (create_makefile): ignore rest from first dot from diff --git a/bignum.c b/bignum.c index 2f804db5df..ede0de6523 100644 --- a/bignum.c +++ b/bignum.c @@ -2157,15 +2157,15 @@ bigmul1_karatsuba(VALUE x, VALUE y) t3 = bigmul0(xh, yh); i = xn + yn - n; + /* subtract t1 from t3 */ + bigsub_core(BDIGITS(t3), big_real_len(t3), BDIGITS(t1), t1n, BDIGITS(t3), big_real_len(t3)); + + /* subtract t2 from t3; t3 is now the middle term of the product */ + if (t2 != Qundef) bigsub_core(BDIGITS(t3), big_real_len(t3), BDIGITS(t2), t2n, BDIGITS(t3), big_real_len(t3)); + /* add t3 to middle bytes of the result (z1) */ bigadd_core(zds + n, i, BDIGITS(t3), big_real_len(t3), zds + n, i); - /* subtract t1 from middle bytes of the result (z1) */ - bigsub_core(zds + n, i, BDIGITS(t1), t1n, zds + n, i); - - /* subtract t2 from middle bytes of the result (z1) */ - if (t2 != Qundef) bigsub_core(zds + n, i, BDIGITS(t2), t2n, zds + n, i); - return z; }