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Commit 9046e401 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
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[S390] mmap: consider stack address randomization 



Consider stack address randomization when calulating mmap_base for
flexible mmap layout . Because of address randomization the stack
address can be up to 8MB lower than STACK_TOP.
When calculating mmap_base this isn't taken into account, which could
lead to the case that the gap between the real stack top and mmap_base
is lower than what ulimit specifies for the maximum stack size.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 7a63fa1a

arch/s390/include/asm/elf.h

+2 −0
Original line number Original line Diff line number Diff line
@@ -206,6 +206,8 @@ do { \ 
	current->mm->context.noexec == 0;		\

	current->mm->context.noexec == 0;		\

})

})





#define STACK_RND_MASK	0x7ffUL



#define ARCH_DLINFO							    \

#define ARCH_DLINFO							    \

do {									    \

do {									    \

	if (vdso_enabled)						    \

	if (vdso_enabled)						    \

arch/s390/mm/mmap.c

+10 −1
Original line number Original line Diff line number Diff line
@@ -30,6 +30,15 @@ 
#include <asm/pgalloc.h>

#include <asm/pgalloc.h>

#include <asm/compat.h>

#include <asm/compat.h>





static unsigned long stack_maxrandom_size(void)

{

	if (!(current->flags & PF_RANDOMIZE))

		return 0;

	if (current->personality & ADDR_NO_RANDOMIZE)

		return 0;

	return STACK_RND_MASK << PAGE_SHIFT;

}



/*

/*

 * Top of mmap area (just below the process stack).

 * Top of mmap area (just below the process stack).

 *

 *
@@ -47,7 +56,7 @@ static inline unsigned long mmap_base(void) 
	else if (gap > MAX_GAP)

	else if (gap > MAX_GAP)

		gap = MAX_GAP;

		gap = MAX_GAP;





	return STACK_TOP - (gap & PAGE_MASK);

	return STACK_TOP - stack_maxrandom_size() - (gap & PAGE_MASK);

}

}





static inline int mmap_is_legacy(void)

static inline int mmap_is_legacy(void)