Integrated: 8339134: Callers of Exceptions::fthrow should ensure exception message lengths avoid the INT_MAX limits of os::vsnprintf

[David Holmes]

On Mon, 4 Nov 2024 07:00:38 GMT, David Holmes <dholmes at openjdk.org> wrote:

> This is mostly an audit of the callers of `Exceptions::fthrow` to ensure unbounded strings can't appear.
> 
> There is a code change in DiagnosticCmd parsing to extend the string length limit already used in part of that code.
> 
> Just to clarify the issue. The size 1024 is an internal buffer limit that `fthrow` uses - it is an implementation detail and not something the caller should think about. It is also not relevant to the underlying problem, which is the size of the buffer needed for the fully expanded format string, which `os::vsnprintf` will try to calculate and report. The intent is to check callers can't hit that underlying `vsnprintf` INT_MAX limit. When your format string only deals with a few symbols and symbols are always < 64K then we know we are nowhere near that INT_MAX limit. If your format string can take a potentially arbitrary (usually from outside) string then it needs to put its own size guard in place using `%*s`.
> 
> Testing:
>  - tier 1-3 (sanity)
> 
> Thanks

This pull request has now been integrated.

Changeset: 8de158ae
Author:    David Holmes <dholmes at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/8de158aefe64d493e107ef310f510bab57beb251
Stats:     50 lines in 9 files changed: 44 ins; 1 del; 5 mod

8339134: Callers of Exceptions::fthrow should ensure exception message lengths avoid the INT_MAX limits of os::vsnprintf

Reviewed-by: coleenp, jsjolen

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PR: https://git.openjdk.org/jdk/pull/21867