> when malloc() returns NULL? That's a crash - a well-behaved one (no UB involved)

Wrong, dereferencing a NULL pointer is UB.

sph 2 days ago | parent [-]

Which on UNIXes is a crash because the zero page is unmapped so you get a SIGSEGV

	▲	1718627440 a day ago \| parent [-]
		Unless the compiler optimized the access away, or replaced it with a different address.