On Fri, 25 Feb 2022 17:35:49 -0800 Kees Cook <keescook@xxxxxxxxxxxx> wrote: > On Fri, Feb 25, 2022 at 04:01:57PM -0800, Andrew Morton wrote: > > On Fri, 25 Feb 2022 09:33:45 -0800 Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > > > > Under CONFIG_HARDENED_USERCOPY=y, when exact stack frame boundary checking > > > is not available (i.e. everything except x86 with FRAME_POINTER), check > > > a stack object as being at least "current depth valid", in the sense > > > that any object within the stack region but not between start-of-stack > > > and current_stack_pointer should be considered unavailable (i.e. its > > > lifetime is from a call no longer present on the stack). > > > > > > Introduce ARCH_HAS_CURRENT_STACK_POINTER to track which architectures > > > have actually implemented the common global register alias. > > > > > > Additionally report usercopy bounds checking failures with an offset > > > from current_stack_pointer, which may assist with diagnosing failures. > > > > > > The LKDTM USERCOPY_STACK_FRAME_TO and USERCOPY_STACK_FRAME_FROM tests > > > (once slightly adjusted in a separate patch) will pass again with > > > this fixed. > > > > Again, what does this actually do? > > [answers] > OK, thanks. I think a new changelog is warranted? What's your preferred path for upstreaming this change?
