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metag: Reduce maximum stack size to 256MB

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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: James 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)
This commit is contained in:
James Hogan 2014-05-13 23:58:24 +01:00
parent 2425ce8402
commit d71f290b4e
3 changed files with 7 additions and 3 deletions
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2
arch/metag/include/asm/processor.h
View file

@ -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.

2
arch/parisc/include/asm/processor.h
View file

@ -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__

6
fs/exec.c
View file

@ -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)