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fix(bytesconv): detect integer overflow before multiplication in ParseUintBuf #1538

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fix(bytesconv): detect integer overflow before multiplication in ParseUintBuf #1538

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10 changes: 6 additions & 4 deletions internal/bytesconv/bytesconv.go
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,7 @@
package bytesconv

import (
"math"
"net/http"
"time"
"unsafe"
Expand Down Expand Up @@ -162,12 +163,13 @@ func ParseUintBuf(b []byte) (int, int, error) {
}
return v, i, nil
}
vNew := 10*v + int(k)
// Test for overflow.
if vNew < v {
// Test for overflow before multiplying, because 10*v may wrap around
// to a value that is still greater than v, which would make a
// post-multiplication check unreliable.
if v > (math.MaxInt-int(k))/10 {
return -1, i, errTooLongInt
}
v = vNew
v = 10*v + int(k)
}
return v, n, nil
}
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6 changes: 6 additions & 0 deletions internal/bytesconv/bytesconv_64_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -104,6 +104,12 @@ func TestParseUintError(t *testing.T) {
{"-9223372036854775808"},
{"9223372036854775808"},
{"18446744073709551615"},
// Values whose intermediate 10*v wraps past 2^64 and lands back on a
// positive number, which a post-multiplication overflow check misses.
{"21000000000000000000"},
{"25000000000000000000"},
{"46000000000000000000"},
{"83000000000000000000"},
} {
n, err := ParseUint(S2b(v.s))
if err == nil {
Expand Down