Re: [PATCH v4 3/3] MIPS: set stack/data protection as non-executable

From: David Daney
Date: Wed Aug 05 2015 - 19:56:12 EST


On 08/05/2015 04:49 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.


NAK.

You cannot change the default.

If you want a non-executable stack, the program has to request it with the proper annotations in its ELF file.

David Daney.


Additionally, it sets a default data area non-executable protection.

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@xxxxxxxxxx>
---
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 89dd7fed1a57..0b6cec4a1b80 100644
--- a/arch/mips/include/asm/page.h
+++ b/arch/mips/include/asm/page.h
@@ -228,7 +228,7 @@ 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)


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