The following errors/warnings in BIND code were produced when running the tests with the code on "master" compiled with gcc using the -fsanitize=undefined option:

* rdata/generic/opt_41.c:195:2: runtime error: null pointer passed as argument 2, which is declared to never be null
* name.c:2053:3: runtime error: null pointer passed as argument 2, which is declared to never be null
* name.c:2545:2: runtime error: null pointer passed as argument 2, which is declared to never be null
* message.c:4404:4: runtime error: null pointer passed as argument 2, which is declared to never be null

All these of these seem to be related to memmove (the last via the macro ISC__BUFFER_PUTMEM); it is likely that although the second argument is null, the third argument is 0, which means that no action is taken.  However, a similar construct back in 2014 caused problems on a new version of gcc because the compiler noted that a pointer was passed as a "not null" argument to a glib function and subsequently optimised away a check protecting the pointer being dereferenced if it was null. (#35968)


* random.c:143:45: runtime error: left shift of 1748803827 by 12 places cannot be represented in type 'int'
* inet_aton.c:177:20: runtime error: left shift of 192 by 24 places cannot be represented in type 'int'

Both these messages appeared a number of times (with different numbers). 


* random_test.c:204:20: runtime error: shift exponent 32 is too large for 32-bit type 'unsigned int'

I've only seen this message once.