Fix for CVE-2014-3570 (with minor bn_asm.c revamp).

Reviewed-by: Emilia Kasper <emilia@openssl.org>

1 files changed, 122 insertions, 119 deletions

diff --git a/crypto/bn/bn_asm.c b/crypto/bn/bn_asm.c
index 14eaf2c62d..5027a58320 100644
--- a/crypto/bn/bn_asm.c
+++ b/crypto/bn/bn_asm.c
@@ -439,116 +439,143 @@ BN_ULONG bn_sub_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b, int n)
 /* sqr_add_c2(a,i,c0,c1,c2) -- c+=2*a[i]*a[j] for three word number c=(c2,c1,c0) */
 
 #ifdef BN_LLONG
-#define mul_add_c(a,b,c0,c1,c2) \
-	t=(BN_ULLONG)a*b; \
-	t1=(BN_ULONG)Lw(t); \
-	t2=(BN_ULONG)Hw(t); \
-	c0=(c0+t1)&BN_MASK2; if ((c0) < t1) t2++; \
-	c1=(c1+t2)&BN_MASK2; if ((c1) < t2) c2++;
-
-#define mul_add_c2(a,b,c0,c1,c2) \
-	t=(BN_ULLONG)a*b; \
-	tt=(t+t)&BN_MASK; \
-	if (tt < t) c2++; \
-	t1=(BN_ULONG)Lw(tt); \
-	t2=(BN_ULONG)Hw(tt); \
-	c0=(c0+t1)&BN_MASK2;  \
-	if ((c0 < t1) && (((++t2)&BN_MASK2) == 0)) c2++; \
-	c1=(c1+t2)&BN_MASK2; if ((c1) < t2) c2++;
-
-#define sqr_add_c(a,i,c0,c1,c2) \
-	t=(BN_ULLONG)a[i]*a[i]; \
-	t1=(BN_ULONG)Lw(t); \
-	t2=(BN_ULONG)Hw(t); \
-	c0=(c0+t1)&BN_MASK2; if ((c0) < t1) t2++; \
-	c1=(c1+t2)&BN_MASK2; if ((c1) < t2) c2++;
+/*
+ * Keep in mind that additions to multiplication result can not
+ * overflow, because its high half cannot be all-ones.
+ */
+#define mul_add_c(a,b,c0,c1,c2)		do {	\
+	BN_ULONG hi;				\
+	BN_ULLONG t = (BN_ULLONG)(a)*(b);	\
+	t += c0;		/* no carry */	\
+	c0 = (BN_ULONG)Lw(t);			\
+	hi = (BN_ULONG)Hw(t);			\
+	c1 = (c1+hi)&BN_MASK2; if (c1<hi) c2++;	\
+	} while(0)
+
+#define mul_add_c2(a,b,c0,c1,c2)	do {	\
+	BN_ULONG hi;				\
+	BN_ULLONG t = (BN_ULLONG)(a)*(b);	\
+	BN_ULLONG tt = t+c0;	/* no carry */	\
+	c0 = (BN_ULONG)Lw(tt);			\
+	hi = (BN_ULONG)Hw(tt);			\
+	c1 = (c1+hi)&BN_MASK2; if (c1<hi) c2++;	\
+	t += c0;		/* no carry */	\
+	c0 = (BN_ULONG)Lw(t);			\
+	hi = (BN_ULONG)Hw(t);			\
+	c1 = (c1+hi)&BN_MASK2; if (c1<hi) c2++;	\
+	} while(0)
+
+#define sqr_add_c(a,i,c0,c1,c2)		do {	\
+	BN_ULONG hi;				\
+	BN_ULLONG t = (BN_ULLONG)a[i]*a[i];	\
+	t += c0;		/* no carry */	\
+	c0 = (BN_ULONG)Lw(t);			\
+	hi = (BN_ULONG)Hw(t);			\
+	c1 = (c1+hi)&BN_MASK2; if (c1<hi) c2++;	\
+	} while(0)
 
 #define sqr_add_c2(a,i,j,c0,c1,c2) \
 	mul_add_c2((a)[i],(a)[j],c0,c1,c2)
 
 #elif defined(BN_UMULT_LOHI)
-
-#define mul_add_c(a,b,c0,c1,c2)	{	\
-	BN_ULONG ta=(a),tb=(b);		\
-	BN_UMULT_LOHI(t1,t2,ta,tb);	\
-	c0 += t1; t2 += (c0<t1)?1:0;	\
-	c1 += t2; c2 += (c1<t2)?1:0;	\
-	}
-
-#define mul_add_c2(a,b,c0,c1,c2) {	\
-	BN_ULONG ta=(a),tb=(b),t0;	\
-	BN_UMULT_LOHI(t0,t1,ta,tb);	\
-	t2 = t1+t1; c2 += (t2<t1)?1:0;	\
-	t1 = t0+t0; t2 += (t1<t0)?1:0;	\
-	c0 += t1; t2 += (c0<t1)?1:0;	\
-	c1 += t2; c2 += (c1<t2)?1:0;	\
-	}
-
-#define sqr_add_c(a,i,c0,c1,c2)	{	\
-	BN_ULONG ta=(a)[i];		\
-	BN_UMULT_LOHI(t1,t2,ta,ta);	\
-	c0 += t1; t2 += (c0<t1)?1:0;	\
-	c1 += t2; c2 += (c1<t2)?1:0;	\
-	}
+/*
+ * Keep in mind that additions to hi can not overflow, because
+ * the high word of a multiplication result cannot be all-ones.
+ */
+#define mul_add_c(a,b,c0,c1,c2)		do {	\
+	BN_ULONG ta = (a), tb = (b);		\
+	BN_ULONG lo, hi;			\
+	BN_UMULT_LOHI(lo,hi,ta,tb);		\
+	c0 += lo; hi += (c0<lo)?1:0;		\
+	c1 += hi; c2 += (c1<hi)?1:0;		\
+	} while(0)
+
+#define mul_add_c2(a,b,c0,c1,c2)	do {	\
+	BN_ULONG ta = (a), tb = (b);		\
+	BN_ULONG lo, hi, tt;			\
+	BN_UMULT_LOHI(lo,hi,ta,tb);		\
+	c0 += lo; tt = hi+((c0<lo)?1:0);	\
+	c1 += tt; c2 += (c1<tt)?1:0;		\
+	c0 += lo; hi += (c0<lo)?1:0;		\
+	c1 += hi; c2 += (c1<hi)?1:0;		\
+	} while(0)
+
+#define sqr_add_c(a,i,c0,c1,c2)		do {	\
+	BN_ULONG ta = (a)[i];			\
+	BN_ULONG lo, hi;			\
+	BN_UMULT_LOHI(lo,hi,ta,ta);		\
+	c0 += lo; hi += (c0<lo)?1:0;		\
+	c1 += hi; c2 += (c1<hi)?1:0;		\
+	} while(0)
 
 #define sqr_add_c2(a,i,j,c0,c1,c2)	\
 	mul_add_c2((a)[i],(a)[j],c0,c1,c2)
 
 #elif defined(BN_UMULT_HIGH)
-
-#define mul_add_c(a,b,c0,c1,c2)	{	\
-	BN_ULONG ta=(a),tb=(b);		\
-	t1 = ta * tb;			\
-	t2 = BN_UMULT_HIGH(ta,tb);	\
-	c0 += t1; t2 += (c0<t1)?1:0;	\
-	c1 += t2; c2 += (c1<t2)?1:0;	\
-	}
-
-#define mul_add_c2(a,b,c0,c1,c2) {	\
-	BN_ULONG ta=(a),tb=(b),t0;	\
-	t1 = BN_UMULT_HIGH(ta,tb);	\
-	t0 = ta * tb;			\
-	t2 = t1+t1; c2 += (t2<t1)?1:0;	\
-	t1 = t0+t0; t2 += (t1<t0)?1:0;	\
-	c0 += t1; t2 += (c0<t1)?1:0;	\
-	c1 += t2; c2 += (c1<t2)?1:0;	\
-	}
-
-#define sqr_add_c(a,i,c0,c1,c2)	{	\
-	BN_ULONG ta=(a)[i];		\
-	t1 = ta * ta;			\
-	t2 = BN_UMULT_HIGH(ta,ta);	\
-	c0 += t1; t2 += (c0<t1)?1:0;	\
-	c1 += t2; c2 += (c1<t2)?1:0;	\
-	}
+/*
+ * Keep in mind that additions to hi can not overflow, because
+ * the high word of a multiplication result cannot be all-ones.
+ */
+#define mul_add_c(a,b,c0,c1,c2)		do {	\
+	BN_ULONG ta = (a), tb = (b);		\
+	BN_ULONG lo = ta * tb;			\
+	BN_ULONG hi = BN_UMULT_HIGH(ta,tb);	\
+	c0 += lo; hi += (c0<lo)?1:0;		\
+	c1 += hi; c2 += (c1<hi)?1:0;		\
+	} while(0)
+
+#define mul_add_c2(a,b,c0,c1,c2)	do {	\
+	BN_ULONG ta = (a), tb = (b), tt;	\
+	BN_ULONG lo = ta * tb;			\
+	BN_ULONG hi = BN_UMULT_HIGH(ta,tb);	\
+	c0 += lo; tt = hi + ((c0<lo)?1:0);	\
+	c1 += tt; c2 += (c1<tt)?1:0;		\
+	c0 += lo; hi += (c0<lo)?1:0;		\
+	c1 += hi; c2 += (c1<hi)?1:0;		\
+	} while(0)
+
+#define sqr_add_c(a,i,c0,c1,c2)		do {	\
+	BN_ULONG ta = (a)[i];			\
+	BN_ULONG lo = ta * ta;			\
+	BN_ULONG hi = BN_UMULT_HIGH(ta,ta);	\
+	c0 += lo; hi += (c0<lo)?1:0;		\
+	c1 += hi; c2 += (c1<hi)?1:0;		\
+	} while(0)
 
 #define sqr_add_c2(a,i,j,c0,c1,c2)	\
 	mul_add_c2((a)[i],(a)[j],c0,c1,c2)
 
 #else /* !BN_LLONG */
-#define mul_add_c(a,b,c0,c1,c2) \
-	t1=LBITS(a); t2=HBITS(a); \
-	bl=LBITS(b); bh=HBITS(b); \
-	mul64(t1,t2,bl,bh); \
-	c0=(c0+t1)&BN_MASK2; if ((c0) < t1) t2++; \
-	c1=(c1+t2)&BN_MASK2; if ((c1) < t2) c2++;
-
-#define mul_add_c2(a,b,c0,c1,c2) \
-	t1=LBITS(a); t2=HBITS(a); \
-	bl=LBITS(b); bh=HBITS(b); \
-	mul64(t1,t2,bl,bh); \
-	if (t2 & BN_TBIT) c2++; \
-	t2=(t2+t2)&BN_MASK2; \
-	if (t1 & BN_TBIT) t2++; \
-	t1=(t1+t1)&BN_MASK2; \
-	c0=(c0+t1)&BN_MASK2;  \
-	if ((c0 < t1) && (((++t2)&BN_MASK2) == 0)) c2++; \
-	c1=(c1+t2)&BN_MASK2; if ((c1) < t2) c2++;
-
-#define sqr_add_c(a,i,c0,c1,c2) \
-	sqr64(t1,t2,(a)[i]); \
-	c0=(c0+t1)&BN_MASK2; if ((c0) < t1) t2++; \
-	c1=(c1+t2)&BN_MASK2; if ((c1) < t2) c2++;
+/*
+ * Keep in mind that additions to hi can not overflow, because
+ * the high word of a multiplication result cannot be all-ones.
+ */
+#define mul_add_c(a,b,c0,c1,c2)		do {	\
+	BN_ULONG lo = LBITS(a), hi = HBITS(a);	\
+	BN_ULONG bl = LBITS(b), bh = HBITS(b);	\
+	mul64(lo,hi,bl,bh);			\
+	c0 = (c0+lo)&BN_MASK2; if (c0<lo) hi++;	\
+	c1 = (c1+hi)&BN_MASK2; if (c1<hi) c2++;	\
+	} while(0)
+
+#define mul_add_c2(a,b,c0,c1,c2)	do {	\
+	BN_ULONG tt;				\
+	BN_ULONG lo = LBITS(a), hi = HBITS(a);	\
+	BN_ULONG bl = LBITS(b), bh = HBITS(b);	\
+	mul64(lo,hi,bl,bh);			\
+	tt = hi;				\
+	c0 = (c0+lo)&BN_MASK2; if (c0<lo) tt++;	\
+	c1 = (c1+tt)&BN_MASK2; if (c1<tt) c2++;	\
+	c0 = (c0+lo)&BN_MASK2; if (c0<lo) hi++;	\
+	c1 = (c1+hi)&BN_MASK2; if (c1<hi) c2++;	\
+	} while(0)
+
+#define sqr_add_c(a,i,c0,c1,c2)		do {	\
+	BN_ULONG lo, hi;			\
+	sqr64(lo,hi,(a)[i]);			\
+	c0 = (c0+lo)&BN_MASK2; if (c0<lo) hi++;	\
+	c1 = (c1+hi)&BN_MASK2; if (c1<hi) c2++;	\
+	} while(0)
 
 #define sqr_add_c2(a,i,j,c0,c1,c2) \
 	mul_add_c2((a)[i],(a)[j],c0,c1,c2)
@@ -556,12 +583,6 @@ BN_ULONG bn_sub_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b, int n)
 
 void bn_mul_comba8(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b)
 	{
-#ifdef BN_LLONG
-	BN_ULLONG t;
-#else
-	BN_ULONG bl,bh;
-#endif
-	BN_ULONG t1,t2;
 	BN_ULONG c1,c2,c3;
 
 	c1=0;
@@ -665,12 +686,6 @@ void bn_mul_comba8(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b)
 
 void bn_mul_comba4(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b)
 	{
-#ifdef BN_LLONG
-	BN_ULLONG t;
-#else
-	BN_ULONG bl,bh;
-#endif
-	BN_ULONG t1,t2;
 	BN_ULONG c1,c2,c3;
 
 	c1=0;
@@ -710,12 +725,6 @@ void bn_mul_comba4(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b)
 
 void bn_sqr_comba8(BN_ULONG *r, const BN_ULONG *a)
 	{
-#ifdef BN_LLONG
-	BN_ULLONG t,tt;
-#else
-	BN_ULONG bl,bh;
-#endif
-	BN_ULONG t1,t2;
 	BN_ULONG c1,c2,c3;
 
 	c1=0;
@@ -791,12 +800,6 @@ void bn_sqr_comba8(BN_ULONG *r, const BN_ULONG *a)
 
 void bn_sqr_comba4(BN_ULONG *r, const BN_ULONG *a)
 	{
-#ifdef BN_LLONG
-	BN_ULLONG t,tt;
-#else
-	BN_ULONG bl,bh;
-#endif
-	BN_ULONG t1,t2;
 	BN_ULONG c1,c2,c3;
 
 	c1=0;