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Commit 3abc9448 authored by Vineet Gupta's avatar Vineet Gupta
Browse files

ARC: [mm] Make stack/heap Non-executable by default 



1. For VM_EXEC based delayed dcache/icache flush, reduces the number of
   flushes.

2. Makes this security feature ON by default rather than OFF before.

3. Applications can use mprotect() to selectively override this.

4. ELF binaries have a GNU_STACK segment which can easily override the
   kernel default permissions.
   For nested-functions/trampolines, gcc already auto-enables executable
   stack in elf. Others needing this can use -Wl,-z,execstack option.

Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent 2ed21dae

arch/arc/Kconfig

+0 −7
Original line number Diff line number Diff line
@@ -362,13 +362,6 @@ config ARC_MISALIGN_ACCESS 
	  Use ONLY-IF-ABS-NECESSARY as it will be very slow and also can hide

	  potential bugs in code



config ARC_STACK_NONEXEC

	bool "Make stack non-executable"

	default n

	help

	  To disable the execute permissions of stack/heap of processes

	  which are enabled by default.



config HZ

	int "Timer Frequency"

	default 100

arch/arc/include/asm/page.h

+1 −6
Original line number Diff line number Diff line
@@ -96,13 +96,8 @@ typedef unsigned long pgtable_t; 


#define virt_addr_valid(kaddr)  pfn_valid(__pa(kaddr) >> PAGE_SHIFT)



/* Default Permissions for page, used in mmap.c */

#ifdef CONFIG_ARC_STACK_NONEXEC

/* Default Permissions for stack/heaps pages (Non Executable) */

#define VM_DATA_DEFAULT_FLAGS   (VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE)

#else

#define VM_DATA_DEFAULT_FLAGS   (VM_READ | VM_WRITE | VM_EXEC | \

				 VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)

#endif



#define WANT_PAGE_VIRTUAL   1