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Commit d71f290b authored by James Hogan's avatar James Hogan
Browse files

metag: Reduce maximum stack size to 256MB 



Specify the maximum stack size for arches where the stack grows upward
(parisc and metag) in asm/processor.h rather than hard coding in
fs/exec.c so that metag can specify a smaller value of 256MB rather than
1GB.

This fixes a BUG on metag if the RLIMIT_STACK hard limit is increased
beyond a safe value by root. E.g. when starting a process after running
"ulimit -H -s unlimited" it will then attempt to use a stack size of the
maximum 1GB which is far too big for metag's limited user virtual
address space (stack_top is usually 0x3ffff000):

BUG: failure at fs/exec.c:589/shift_arg_pages()!

Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: linux-parisc@vger.kernel.org
Cc: linux-metag@vger.kernel.org
Cc: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org # only needed for >= v3.9 (arch/metag)
parent 2425ce84

arch/metag/include/asm/processor.h

+2 −0
Original line number Diff line number Diff line
@@ -22,6 +22,8 @@ 
/* Add an extra page of padding at the top of the stack for the guard page. */

#define STACK_TOP	(TASK_SIZE - PAGE_SIZE)

#define STACK_TOP_MAX	STACK_TOP

/* Maximum virtual space for stack */

#define STACK_SIZE_MAX	(1 << 28)	/* 256 MB */



/* This decides where the kernel will search for a free chunk of vm

 * space during mmap's.

arch/parisc/include/asm/processor.h

+2 −0
Original line number Diff line number Diff line
@@ -55,6 +55,8 @@ 
#define STACK_TOP	TASK_SIZE

#define STACK_TOP_MAX	DEFAULT_TASK_SIZE



#define STACK_SIZE_MAX	(1 << 30)	/* 1 GB */



#endif



#ifndef __ASSEMBLY__

fs/exec.c

+3 −3
Original line number Diff line number Diff line
@@ -657,10 +657,10 @@ int setup_arg_pages(struct linux_binprm *bprm, 
	unsigned long rlim_stack;



#ifdef CONFIG_STACK_GROWSUP

	/* Limit stack size to 1GB */

	/* Limit stack size */

	stack_base = rlimit_max(RLIMIT_STACK);

	if (stack_base > (1 << 30))

		stack_base = 1 << 30;

	if (stack_base > STACK_SIZE_MAX)

		stack_base = STACK_SIZE_MAX;



	/* Make sure we didn't let the argument array grow too large. */

	if (vma->vm_end - vma->vm_start > stack_base)