On Fri, Feb 25, 2022 at 03:45:18PM -0800, Andrew Morton wrote: > On Fri, 25 Feb 2022 14:16:25 -0800 Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > > If ksize() is used on an allocation, the compiler cannot make any > > assumptions about its size any more (as hinted by __alloc_size). Force > > it to forget. > > > > One caller was using a container_of() construction that needed to be > > worked around. > > Please, when fixing something do fully explain what that thing is. I, > for one, simply cannot understand why this change is being proposed. > > Especially when proposing a -stable backport! Tell readers what was > the end-user impact of the bug. > > > Link: https://github.com/ClangBuiltLinux/linux/issues/1599 > > Even that didn't tell me. Is it just a clang warning? Does the kernel > post your private keys on reddit then scribble all over your disk > drive? I dunno. Yup, sorry. I tend to get so deep changes like this that I forget to give an appropriately detailed summary. As others have mentioned, this is trying to fix a miscompilation issue, triggered by what can be considered either a mis-application of __alloc_size, or a failure to correctly disable compiler optimizations in the face of ksize(). -- Kees Cook
