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* bignum.c (bigsub_int): Fix a buffer over read.

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git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41631 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
akr 2013-06-25 16:18:32 +00:00
parent 56435700df
commit 4d906fbc14
2 changed files with 58 additions and 9 deletions
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4
ChangeLog
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@ -1,3 +1,7 @@
Wed Jun 26 01:17:29 2013 Tanaka Akira <akr@fsij.org>
* bignum.c (bigsub_int): Fix a buffer over read.
Tue Jun 25 22:45:43 2013 Tanaka Akira <akr@fsij.org>
* bignum.c (rb_absint_singlebit_p): Use POW2_P.

63
bignum.c
View File

@ -3091,7 +3091,7 @@ bigsub_int(VALUE x, long y0)
{
VALUE z;
BDIGIT *xds, *zds;
long xn;
long xn, zn;
BDIGIT_DBL_SIGNED num;
long i, y;
@ -3099,10 +3099,19 @@ bigsub_int(VALUE x, long y0)
xds = BDIGITS(x);
xn = RBIGNUM_LEN(x);
z = bignew(xn, RBIGNUM_SIGN(x));
if (xn == 0)
return LONG2NUM(-y0);
zn = xn;
#if SIZEOF_BDIGITS < SIZEOF_LONG
if (zn < bdigit_roomof(SIZEOF_LONG))
zn = bdigit_roomof(SIZEOF_LONG);
#endif
z = bignew(zn, RBIGNUM_SIGN(x));
zds = BDIGITS(z);
#if SIZEOF_BDIGITS >= SIZEOF_LONG
assert(xn == zn);
num = (BDIGIT_DBL_SIGNED)xds[0] - y;
if (xn == 1 && num < 0) {
RBIGNUM_SET_SIGN(z, !RBIGNUM_SIGN(x));
@ -3113,26 +3122,62 @@ bigsub_int(VALUE x, long y0)
zds[0] = BIGLO(num);
num = BIGDN(num);
i = 1;
if (i < xn)
goto y_is_zero_x;
goto finish;
#else
num = 0;
for (i=0; i<bdigit_roomof(SIZEOF_LONG); i++) {
for (i=0; i < xn; i++) {
if (y == 0) goto y_is_zero_x;
num += (BDIGIT_DBL_SIGNED)xds[i] - BIGLO(y);
zds[i] = BIGLO(num);
num = BIGDN(num);
y = BIGDN(y);
}
for (; i < zn; i++) {
if (y == 0) goto y_is_zero_z;
num -= BIGLO(y);
zds[i] = BIGLO(num);
num = BIGDN(num);
y = BIGDN(y);
}
goto finish;
#endif
while (num && i < xn) {
for (; i < xn; i++) {
y_is_zero_x:
if (num == 0) goto num_is_zero_x;
num += xds[i];
zds[i++] = BIGLO(num);
zds[i] = BIGLO(num);
num = BIGDN(num);
}
while (i < xn) {
zds[i] = xds[i];
i++;
#if SIZEOF_BDIGITS < SIZEOF_LONG
for (; i < zn; i++) {
y_is_zero_z:
if (num == 0) goto num_is_zero_z;
zds[i] = BIGLO(num);
num = BIGDN(num);
}
#endif
goto finish;
for (; i < xn; i++) {
num_is_zero_x:
zds[i] = xds[i];
}
#if SIZEOF_BDIGITS < SIZEOF_LONG
for (; i < zn; i++) {
num_is_zero_z:
zds[i] = 0;
}
#endif
goto finish;
finish:
assert(num == 0 || num == -1);
if (num < 0) {
z = bigsub(x, rb_int2big(y0));
get2comp(z);
RBIGNUM_SET_SIGN(z, !RBIGNUM_SIGN(x));
}
RB_GC_GUARD(x);
return bignorm(z);