> From: Dan Carpenter > Sent: 01 October 2019 14:57 > Subject: Re: [PATCH] staging: rtl8723bs: hal: Fix memcpy calls ... > That's true for glibc memcpy() but not for the kernel memcpy(). In the > kernel there are lots of places which do a zero size memcpy(). And probably from NULL (or even garbage) pointers. After all a pointer to the end of an array (a + ARRAY_SIZE(a)) is valid but must not be dereferenced - so memcpy() can't dereference it's source address when the length is zero. > The glibc attitude is "the standard allows us to put knives here" so > let's put knives everywhere in the path. And the GCC attitude is let's > silently remove NULL checks instead of just printing a warning that the > NULL check isn't required... It could really make someone despondent. gcc is the one that add knives... This reminds me of me of a compiler that decided to optimise away checks for function addresses being NULL. At almost exactly the same time that ELF allowed for undefined weak symbols. Checking whether a function was actually present was non-trivial. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
