Arseny KapoulkineDec 11, 2024
This is exciting https://developers.redhat.com/articles/2024/12/11/making-memcpynull-null-0-well-defined
Making memcpy(NULL, NULL, 0) well-defined | Red Hat Developer

C2y makes memcpy(NULL, NULL, 0) and other zero-length operations on null pointers well defined. This removes a source of bugs that may result in security issues

Red Hat Developer
Show threadBilly O'NealDec 11, 2024
@zeux The old behavior was ridiculous. Implementations that failed on that should be ashamed.
Show threadArseny Kapoulkine
@malwareminigun Yeah. I don't even know if implementations that did fail ever existed? All I know is I can stop putting pointless `> 0` checks to appease UBSAN at some point in the future.
Dec 11, 2024 at 8:56pmWeb
Show threadBilly O'NealDec 11, 2024
@zeux I was told by some folks at committee meetings (Marshal Clow?) that both gcc and clang were affected because glibc's declaration of memcpy said that the parameters were not null.
Show threadArseny KapoulkineDec 11, 2024
@malwareminigun Yeah but that affects calling code presumably; I meant that implementations should have always supported this.
Show threadBilly O'NealDec 12, 2024
@zeux Oh, right. "Implementation" to mean means "Implementation of C++" meaning the compiler and standard library together.