[release-branch.go1.16] math/big: prevent overflow in (*Rat).SetString
Credit to rsc@ for the original patch.
Thanks to the OSS-Fuzz project for discovering this
issue and to Emmanuel Odeke (@odeke_et) for reporting it.
Updates #50699
Fixes #50700
Fixes CVE-2022-23772
Change-Id: I590395a3d55689625390cf1e58f5f40623b26ee5
Reviewed-on: https://go-review.googlesource.com/c/go/+/379537
Trust: Katie Hockman <katie@golang.org>
Run-TryBot: Katie Hockman <katie@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emmanuel@orijtech.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
Reviewed-by: Julie Qiu <julie@golang.org>
(cherry picked from commit
ad345c265916bbf6c646865e4642eafce6d39e78)
Reviewed-on: https://go-review.googlesource.com/c/go/+/381337