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The gcc by default assumes executable stack is required if the source object file doesn't have .note.GNU-stack section in place. If any of the source objects doesn't incorporate the GNU-stack note, the resulting program will have executable stack flag set in PT_GNU_STACK program header to instruct program loader or kernel to set up the executable stack when program loads to memory. Usually the .note.GNU-stack section will be generated by gcc automatically if it finds that executable stack is not required. However it doesn't take care of generating .note.GNU-stack section for those object files built from assembler sources. This leads to unnecessary risk of security of exploiting the executable stack because those assembler sources don't actually require stack to be executable to work. The grub-emu and grub-emu-lite are found to flag stack as executable revealed by execstack tool. $ mkdir -p build-emu && cd build-emu $ ../configure --with-platform=emu && make $ execstack -q grub-core/grub-emu grub-core/grub-emu-lite X grub-core/grub-emu X grub-core/grub-emu-lite This patch will add the missing GNU-stack note to the assembler source used by both utilities, therefore the result doesn't count on gcc default behavior and the executable stack is disabled. $ execstack -q grub-core/grub-emu grub-core/grub-emu-lite - grub-core/grub-emu - grub-core/grub-emu-lite Signed-off-by: Michael Chang <mchang@suse.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This is GRUB 2, the second version of the GRand Unified Bootloader. GRUB 2 is rewritten from scratch to make GNU GRUB cleaner, safer, more robust, more powerful, and more portable. See the file NEWS for a description of recent changes to GRUB 2. See the file INSTALL for instructions on how to build and install the GRUB 2 data and program files. See the file MAINTAINERS for information about the GRUB maintainers, etc. If you found a security vulnerability in the GRUB please check the SECURITY file to get more information how to properly report this kind of bugs to the maintainers. Please visit the official web page of GRUB 2, for more information. The URL is <http://www.gnu.org/software/grub/grub.html>. More extensive documentation is available in the Info manual, accessible using 'info grub' after building and installing GRUB 2. There are a number of important user-visible differences from the first version of GRUB, now known as GRUB Legacy. For a summary, please see: info grub Introduction 'Changes from GRUB Legacy'