[Bug sanitizer/68065] Size calculations for VLAs can overflow

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68065

--- Comment #34 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
On Thu, 19 Nov 2015, ch3root at openwall dot com wrote:

> What does the following mean then?
> 
> C11, 4p5:
> "A strictly conforming program[...] It [...] shall not exceed any 
> minimum implementation limit."

It's well-known that, if you read the standard literally, strictly 
conforming programs may not exist; too much is unspecified or 
implementation-defined (including, in general, limits on supported 
programs; cf 1#2 "This International Standard does not specify ... the 
size or complexity of a program and its data that will exceed the capacity 
of any specific data-processing system or the capacity of a particular 
processor").

In general, you can only reason about C programs conditional on the 
program not exceeding any implementation limit.