On Wed, Mar 02, 2022 at 12:18:45PM -0800, Linus Torvalds wrote: > On Wed, Mar 2, 2022 at 12:07 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > > > I've long wanted to change kfree() to explicitly set pointers to NULL on > > free. https://github.com/KSPP/linux/issues/87 > > We've had this discussion with the gcc people in the past, and gcc > actually has some support for it, but it's sadly tied to the actual > function name (ie gcc has some special-casing for "free()") > > See > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94527 > > for some of that discussion. > > Oh, and I see some patch actually got merged since I looked there last > so that you can mark "deallocator" functions, but I think it's only > for the context matching, not for actually killing accesses to the > pointer afterwards. Ah! I missed that getting added in GCC 11. But yes, there it is: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute Hah, now we may need to split __malloc from __alloc_size. ;) I'd still like the NULL assignment behavior, though, since some things can easily avoid static analysis. -- Kees Cook
