diff options
| -rw-r--r-- | src/backend/utils/adt/numeric.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c index fe9f3f7a506..dcdc5cf8300 100644 --- a/src/backend/utils/adt/numeric.c +++ b/src/backend/utils/adt/numeric.c @@ -6266,8 +6266,14 @@ div_var_fast(NumericVar *var1, NumericVar *var2, NumericVar *result, /* * maxdiv tracks the maximum possible absolute value of any div[] entry; * when this threatens to exceed INT_MAX, we take the time to propagate - * carries. To avoid overflow in maxdiv itself, it actually represents - * the max possible abs. value divided by NBASE-1. + * carries. Furthermore, we need to ensure that overflow doesn't occur + * during the carry propagation passes either. The carry values may have + * an absolute value as high as INT_MAX/NBASE + 1, so really we must + * normalize when digits threaten to exceed INT_MAX - INT_MAX/NBASE - 1. + * + * To avoid overflow in maxdiv itself, it represents the max absolute + * value divided by NBASE-1, ie, at the top of the loop it is known that + * no div[] entry has an absolute value exceeding maxdiv * (NBASE-1). */ maxdiv = 1; @@ -6293,7 +6299,7 @@ div_var_fast(NumericVar *var1, NumericVar *var2, NumericVar *result, { /* Do we need to normalize now? */ maxdiv += Abs(qdigit); - if (maxdiv > INT_MAX / (NBASE - 1)) + if (maxdiv > (INT_MAX - INT_MAX / NBASE - 1) / (NBASE - 1)) { /* Yes, do it */ carry = 0; |