math/big: (*Rat).SetString with "1.770p02041010010011001001" crashes with "makeslice: len out of range" #45910
Description
What version of Go are you using (go version)?
Go since Go1.13 when we added support for hexadecimal literals
Does this issue reproduce with the latest release?
Yes!
What operating system and processor architecture are you using (go env)?
Not applicable, present on all versions
What did you do?
Found by oss-fuzz https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=33284, I ran the code in https://play.golang.org/p/pM4ROalIRvq or inlined below
package main
import "math/big"
func main() {
r := new(big.Rat)
r.SetString("1.770p02041010010011001001")
}What did you expect to see?
No crash but the boolean value returned as false.
What did you see instead?
A crash resulting from us having passed in 31890781406421892 in make.
$ go run main.go
panic: runtime error: makeslice: len out of range
goroutine 1 [running]:
math/big.nat.make(...)
/Users/emmanuelodeke/go/src/go.googlesource.com/go/src/math/big/nat.go:69
math/big.nat.shl({0xc000136008, 0x0, 0x0}, {0xc000136008, 0xc000140000, 0x0}, 0x113b270)
/Users/emmanuelodeke/go/src/go.googlesource.com/go/src/math/big/nat.go:1010 +0x213
math/big.(*Rat).SetString(0xc00012bf30, {0x10b527e, 0xc0000001a0})
/Users/emmanuelodeke/go/src/go.googlesource.com/go/src/math/big/ratconv.go:188 +0x756
main.main()
/Users/emmanuelodeke/Desktop/openSrc/bugs/golang/oss-fuzz/33284/main.go:7 +0x49
exit status 2We should perhaps cap the value that we pass into make to avoid an OOM.
Kindly cc-ing @griesemer @findleyr @katiehockman @rolandshoemaker @FiloSottile