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-rw-r--r--crypto/bn/bn_asm.c16
1 files changed, 10 insertions, 6 deletions
diff --git a/crypto/bn/bn_asm.c b/crypto/bn/bn_asm.c
index c43c91cc09f4..a33b63411b7f 100644
--- a/crypto/bn/bn_asm.c
+++ b/crypto/bn/bn_asm.c
@@ -438,6 +438,10 @@ BN_ULONG bn_sub_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b, int n)
/* sqr_add_c(a,i,c0,c1,c2) -- c+=a[i]^2 for three word number c=(c2,c1,c0) */
/* sqr_add_c2(a,i,c0,c1,c2) -- c+=2*a[i]*a[j] for three word number c=(c2,c1,c0) */
+/*
+ * Keep in mind that carrying into high part of multiplication result
+ * can not overflow, because it cannot be all-ones.
+ */
#ifdef BN_LLONG
#define mul_add_c(a,b,c0,c1,c2) \
t=(BN_ULLONG)a*b; \
@@ -478,10 +482,10 @@ BN_ULONG bn_sub_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b, int n)
#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; \
+ c0 += t0; t2 = t1+((c0<t0)?1:0);\
c1 += t2; c2 += (c1<t2)?1:0; \
+ c0 += t0; t1 += (c0<t0)?1:0; \
+ c1 += t1; c2 += (c1<t1)?1:0; \
}
#define sqr_add_c(a,i,c0,c1,c2) { \
@@ -508,10 +512,10 @@ BN_ULONG bn_sub_words(BN_ULONG *r, const BN_ULONG *a, const BN_ULONG *b, int n)
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; \
+ c0 += t0; t2 = t1+((c0<t0)?1:0);\
c1 += t2; c2 += (c1<t2)?1:0; \
+ c0 += t0; t1 += (c0<t0)?1:0; \
+ c1 += t1; c2 += (c1<t1)?1:0; \
}
#define sqr_add_c(a,i,c0,c1,c2) { \