Re: NULL pointer arithmetic issues

[Taylor R Campbell <campbell+netbsd-tech-kern%mumble.net@localhost>]

> Date: Sat, 22 Feb 2020 17:25:42 +0100
> From: Kamil Rytarowski <n54%gmx.com@localhost>
> 
> When running the ATF tests under MKLIBCSANITIZER [1], there are many
> NULL pointer arithmetic issues .
> 
> http://netbsd.org/~kamil/mksanitizer-reports/ubsan-2020-02-22-null-pointer.txt
> 
> These issues are in macros like:
>  - IN_ADDRHASH_READER_FOREACH()
>  - IN_ADDRLIST_WRITER_INSERT_TAIL()
>  - IFADDR_READER_FOREACH()
>  - etc
> 
> These macros wrap internally pserialize-safe linked lists.
> 
> What's the proper approach to address this issue?

What do these reports mean?

UBSan: Undefined Behavior in /usr/src/sys/rump/net/lib/libnet/../../../../netinet6/in6.c:2351:2, pointer expression with base 0 overflowed to 0