From 7b40b0c3a332cbfaa1eb17bdafd2ddf12119ec45 Mon Sep 17 00:00:00 2001 From: Emmanuel Odeke Date: Wed, 28 Sep 2016 01:54:38 -0700 Subject: strings, bytes: panic if Repeat overflows or if given a negative count Panic if Repeat is given a negative count or if the value of (len(*) * count) is detected to overflow. We panic because we cannot change the signature of Repeat to return an error. Fixes #16237 Change-Id: I9f5ba031a5b8533db0582d7a672ffb715143f3fb Reviewed-on: https://go-review.googlesource.com/29954 Run-TryBot: Brad Fitzpatrick TryBot-Result: Gobot Gobot Reviewed-by: Brad Fitzpatrick --- src/bytes/bytes.go | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'src/bytes/bytes.go') diff --git a/src/bytes/bytes.go b/src/bytes/bytes.go index 3286ca3fe9..21405d6004 100644 --- a/src/bytes/bytes.go +++ b/src/bytes/bytes.go @@ -365,7 +365,20 @@ func Map(mapping func(r rune) rune, s []byte) []byte { } // Repeat returns a new byte slice consisting of count copies of b. +// +// It panics if count is negative or if +// the result of (len(b) * count) overflows. func Repeat(b []byte, count int) []byte { + // Since we cannot return an error on overflow, + // we should panic if the repeat will generate + // an overflow. + // See Issue golang.org/issue/16237. + if count < 0 { + panic("bytes: negative Repeat count") + } else if count > 0 && len(b)*count/count != len(b) { + panic("bytes: Repeat count causes overflow") + } + nb := make([]byte, len(b)*count) bp := copy(nb, b) for bp < len(nb) { -- cgit v1.3