On Wed, Jun 02, 2021 at 09:15:02PM +0100, Russell King (Oracle) wrote: > On Wed, Jun 02, 2021 at 09:43:32PM +0300, Mike Rapoport wrote: > > Back then when __ex_table was moved from .data section, _sdata and _edata > > were part of the .data section. Today they are not. So something like the > > patch below will ensure for instance that __ex_table would be a part of > > "Kernel data" in /proc/iomem without moving it to the .data section: > > > This example has undesirable security implications. It moves the > exception table out of the read-only mappings into the read-write > mappings, thereby providing a way for an attacker to bypass the > read-only protection on the kernel and manipulate code pointers at > potentially known addresses for distro built kernels. My point was that __ex_table can be in "Kernel data" or "Kernel rodata" without loosing the ability to sort it. > You seem to be missing the point I've tried to make. The areas in > memblock that are marked "reserved" are the areas of reserved memory > from the firmware _plus_ the areas that the kernel has made during > boot which are of no consequence to userspace. I know what areas are marked "reserved" in memblock. I never suggested to report "ficticious" reserved areas in /proc/iomem unless an architecture already reports them there, like arm64 for example. You are right I should have described better the overall objective, but sill I feel that we keep missing each other points. I'll update the descriptions for the next repost, hopefully it'll help. -- Sincerely yours, Mike.
