On Fri, Dec 5, 2014 at 9:28 AM, David Daney <ddaney.cavm@xxxxxxxxx> wrote: > On 12/02/2014 05:58 PM, Leonid Yegoshin wrote: >> >> This is a last step of 3 patches which shift FPU emulation out of >> stack into protected area. So, it disables a default executable stack. >> >> Additionally, it sets a default data area non-executable protection. >> >> Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@xxxxxxxxxx> > > > NAK! > > Some programs require an executable stack, this patch will break them. Have you tested this? > You can only select a non-executable stack in response to PT_GNU_STACK > program headers in the ELF file of the executable program. This is already handled by fs/binfmt_elf.c. It does the parsing of the PT_GNU_STACK needs, and sets up the stack flags appropriately. All the change to VM_DATA_DEFAULT_FLAGS does is make sure that EXSTACK_DEFAULT now means no VM_EXEC by default. If PT_GNU_STACK requires it, it gets added back in. -Kees > > David Daney > > > >> --- >> arch/mips/include/asm/page.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h >> index 3be81803595d..d49ba81cb4ed 100644 >> --- a/arch/mips/include/asm/page.h >> +++ b/arch/mips/include/asm/page.h >> @@ -230,7 +230,7 @@ extern int __virt_addr_valid(const volatile void >> *kaddr); >> #define virt_addr_valid(kaddr) >> \ >> __virt_addr_valid((const volatile void *) (kaddr)) >> >> -#define VM_DATA_DEFAULT_FLAGS (VM_READ | VM_WRITE | VM_EXEC | \ >> +#define VM_DATA_DEFAULT_FLAGS (VM_READ | VM_WRITE | \ >> VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC) >> >> #define UNCAC_ADDR(addr) ((addr) - PAGE_OFFSET + UNCAC_BASE) >> >> >> >> > -- Kees Cook Chrome OS Security
