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fix: reject a duration sum that wraps past 2^64 #312

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Merged
fredbi merged 1 commit into from
Oct 2, 2026
Merged

fix: reject a duration sum that wraps past 2^64 #312

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6 changes: 6 additions & 0 deletions duration.go
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Original file line number Diff line number Diff line change
Expand Up @@ -240,6 +240,12 @@ func ParseDuration(s string) (time.Duration, error) {
}
}

// The sum is a uint64. 1<<63 ns plus 1<<63 ns wraps to 0, and 0 is not
// greater than maxUint64, so the range check below misses it.
if d > ^uint64(0)-v {
return 0, parseDurationError(orig, "numerical overflow")
}

d += v
if d > maxUint64 {
return 0, parseDurationError(orig, "numerical overflow")
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10 changes: 10 additions & 0 deletions duration_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -256,6 +256,16 @@ func TestDurationParser_Overflow(t *testing.T) {
// time.Duration(math.MinInt64)).
input: "9223372036854775808ns",
},
{
name: "two values of 1<<63 wrap the uint64 sum to zero",
// Each token is 1<<63 ns. The sum is 1<<64, which wraps to 0
// before d > maxUint64 can reject it.
input: "9223372036854775808ns 9223372036854775808ns",
},
{
name: "negative pair of 1<<63 also wraps the uint64 sum to zero",
input: "-9223372036854775808ns 9223372036854775808ns",
},
}

for _, tt := range overflows {
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