On Tue, Nov 16, 2021 at 7:51 PM Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > Have you looked at the output of the compiler to see if this really is > needed or not? No. To do that right you'd need to look at (at least) gcc & clang, multiple architectures (cross-compiled & native) & various levels of optimisation. I just looked at the C code. > And what exactly are you zeroing out that could be read afterward > somehow? Whatever it is, the person who wrote the code thought it was worth zeroing out with memset(). The only question is whether it is safer to use memzero_explicit(). Granted in many cases this will not matter unless the kernel is compiled at some optimisation level that does cross-function analysis so it might be "smart" enough to optimise out the memset(). Also granted it does not matter unless an attacker can look inside the running kernel & if he or she has that level of privilege, then you have much else to worry about. Still, it seemed safer to me to use memzero_explicit() in these cases.
