generic-library/openssl
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Fix a horrible BN bug in bn_expand2 which caused BN_add_word() et al to fail

Browse Source 
when they cause the destination to expand.

To see how evil this is try this:

#include <pem.h>
main()
{
	BIGNUM *bn = NULL;
        int i;
	bn = BN_new();
	BN_hex2bn(&bn, "FFFFFFFF");
	BN_add_word(bn, 1);
	printf("Value %s\n", BN_bn2hex(bn));
}

This would typically fail before the patch.

It also screws up if you comment out the BN_hex2bn line above or in any
situation where BN_add_word() causes the number of BN_ULONGs in the result
to change (try doubling the number of FFs).
This commit is contained in:
Dr. Stephen Henson 1999-04-15 23:07:00 +00:00
parent abed0b8a1f
commit 953937bdc6
2 changed files with 30 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
CHANGES
View File

@ -5,6 +5,10 @@
Changes between 0.9.2b and 0.9.3
*) Fix an evil bug in bn_expand2() which caused various BN functions to
fail when they extended the size of a BIGNUM.
[Steve Henson]
*) Various utility functions to handle SXNet extension. Modify mkdef.pl to
support typesafe stack.
[Steve Henson]

43
crypto/bn/bn_lib.c
View File

@ -376,8 +376,12 @@ int words;
memset(A,0x5c,sizeof(BN_ULONG)*(words+1));
#if 1
B=b->d;
/* Check if the previous number needs to be copied */
if (B != NULL)
{
/* This lot is an unrolled loop to copy b->top
* BN_ULONGs from B to A
*/
for (i=b->top&(~7); i>0; i-=8)
{
A[0]=B[0]; A[1]=B[1]; A[2]=B[2]; A[3]=B[3];
@ -414,30 +418,35 @@ memset(A,0x5c,sizeof(BN_ULONG)*(words+1));
*/
;
}
B= &(b->d[b->top]);
j=b->max-8;
for (i=b->top; i<j; i+=8)
{
B[0]=0; B[1]=0; B[2]=0; B[3]=0;
B[4]=0; B[5]=0; B[6]=0; B[7]=0;
B+=8;
}
for (j+=8; i<j; i++)
{
B[0]=0;
B++;
}
Free(b->d);
}
b->d=a;
b->max=words;
/* Now need to zero any data between b->top and b->max */
B= &(b->d[b->top]);
j=(b->max - b->top) & ~7;
for (i=0; i<j; i+=8)
{
B[0]=0; B[1]=0; B[2]=0; B[3]=0;
B[4]=0; B[5]=0; B[6]=0; B[7]=0;
B+=8;
}
j=(b->max - b->top) & 7;
for (i=0; i<j; i++)
{
B[0]=0;
B++;
}
#else
memcpy(a->d,b->d,sizeof(b->d[0])*b->top);
#endif
/* memset(&(p[b->max]),0,((words+1)-b->max)*sizeof(BN_ULONG)); */
/* { int i; for (i=b->max; i<words+1; i++) p[i]=i;} */
Free(b->d);
}
b->d=a;
b->max=words;
}
return(b);
}