From 07ee9e6445057e181fb3895df978748ffef30327 Mon Sep 17 00:00:00 2001 From: Katie Hockman Date: Wed, 19 Jan 2022 16:54:41 -0500 Subject: [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 Run-TryBot: Katie Hockman TryBot-Result: Gopher Robot Reviewed-by: Emmanuel Odeke Reviewed-by: Roland Shoemaker Reviewed-by: Julie Qiu (cherry picked from commit ad345c265916bbf6c646865e4642eafce6d39e78) Reviewed-on: https://go-review.googlesource.com/c/go/+/381337 --- src/math/big/ratconv.go | 5 +++++ src/math/big/ratconv_test.go | 1 + 2 files changed, 6 insertions(+) diff --git a/src/math/big/ratconv.go b/src/math/big/ratconv.go index ac3c8bd11f..90053a9c81 100644 --- a/src/math/big/ratconv.go +++ b/src/math/big/ratconv.go @@ -169,6 +169,11 @@ func (z *Rat) SetString(s string) (*Rat, bool) { n := exp5 if n < 0 { n = -n + if n < 0 { + // This can occur if -n overflows. -(-1 << 63) would become + // -1 << 63, which is still negative. + return nil, false + } } if n > 1e6 { return nil, false // avoid excessively large exponents diff --git a/src/math/big/ratconv_test.go b/src/math/big/ratconv_test.go index 15d206cb38..e55e655718 100644 --- a/src/math/big/ratconv_test.go +++ b/src/math/big/ratconv_test.go @@ -104,6 +104,7 @@ var setStringTests = []StringTest{ {in: "4/3/"}, {in: "4/3."}, {in: "4/"}, + {in: "13e-9223372036854775808"}, // CVE-2022-23772 // valid {"0", "0", true}, -- cgit v1.2.3-54-g00ecf