JTC 1/SC 22/WG 23 C++ Vulnerability Discussions    WG 23 N1526
		Nov 24 2025

Participants
    Stephen Michell - convenor, SCC
    Erhard Ploedereder - liaison
    Richard Corden - USA

 Regrets
    Peter Sommerlad - Switzerland
    Paul Preney - Canada
    Matt Butler - USA
    Loic Joly - AFNOR

    
Actions:


Issues addressed

 213 - Raised new issue on 6.56 Undefined behaviour 

Clause 6.56 Undefined behaviour updated. Requires review by members.


FROM THE CHAT 2025-11-24:
2025-11-24 10:57:40 From Erhard Ploedereder to Everyone:
	I gear you
	
2025-11-24 10:57:57 From Richard Corden to Everyone:
	```
	
	struct sock *sk = tun->sk; // initialize sk with tun->sk
	…
	if (!tun)
	return POLLERR; // if tun is NULL return error
	```
	
2025-11-24 11:31:50 From Richard Corden to Everyone:
	
	Code with UB may appear to work correctly, however, something	
	* compilers may optimize the code based on assuming UB does not occur resulting
	  in the pruning of code paths for the current version of the compiler, the UB
	  may not manifest as an issue, with a future compiler resulting in consequences
	* the impact of the UB may depend on additional factors, for example the available
	  capacity of a container decides if memory needs to be reallocated the same code
	  used in two different locations, for example a unit test vs production could
	  have different behaviour
	* the impact of overwriting memory often impacts code distant from where the UB
	  occured, resulting in extremely hard to find bugs
	
2025-11-24 11:54:23 From Richard Corden to Everyone:
	where the impact of UB is overwriting memory, changes to source code can result