Avoid allocating large amounts of memory for corrupt input.
No test case because the problem can only happen for invalid data.
Let the fuzzer find cases like this.
Fixes #52521
Change-Id: I6a046f2e28e1255cf773ce135c5bb2b967ef43e9
Reviewed-on: https://go-review.googlesource.com/c/go/+/414234
Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Dan Kortschak <dan@kortschak.io>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>