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bn_word.c: fix overflow bug in BN_add_word.

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This commit is contained in:
Andy Polyakov 2012-11-09 13:58:40 +00:00
parent 8bb870df9e
commit 134c00659a
1 changed files with 8 additions and 17 deletions
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25
crypto/bn/bn_word.c
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@ -144,26 +144,17 @@ int BN_add_word(BIGNUM *a, BN_ULONG w)
a->neg=!(a->neg); a->neg=!(a->neg);
return(i); return(i);
} }
/* Only expand (and risk failing) if it's possibly necessary */ for (i=0;w!=0 && i<a->top;i++)
if (((BN_ULONG)(a->d[a->top - 1] + 1) == 0) &&
(bn_wexpand(a,a->top+1) == NULL))
return(0);
i=0;
for (;;)
{ {
if (i >= a->top) a->d[i] = l = (a->d[i]+w)&BN_MASK2;
l=w; w = (w>l)?1:0;
else
l=(a->d[i]+w)&BN_MASK2;
a->d[i]=l;
if (w > l)
w=1;
else
break;
i++;
} }
if (i >= a->top) if (w && i==a->top)
{
if (bn_wexpand(a,a->top+1) == NULL) return 0;
a->top++; a->top++;
a->d[i]=w;
}
bn_check_top(a); bn_check_top(a);
return(1); return(1);
} }