3.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: James Hogan <james.ho...@imgtec.com>
commit d71f290b4e98a39f49f2595a13be3b4d5ce8e1f1 upstream.
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.ho...@imgtec.com>
Cc: Helge Deller <del...@gmx.de>
Cc: "James E.J. Bottomley" <j...@parisc-linux.org>
Cc: linux-par...@vger.kernel.org
Cc: linux-metag@vger.kernel.org
Cc: John David Anglin <dave.ang...@bell.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/metag/include/asm/processor.h | 2 ++
arch/parisc/include/asm/processor.h | 2 ++
fs/exec.c | 6 +++---
3 files changed, 7 insertions(+), 3 deletions(-)
--- a/arch/metag/include/asm/processor.h
+++ b/arch/metag/include/asm/processor.h
@@ -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.
--- a/arch/parisc/include/asm/processor.h
+++ b/arch/parisc/include/asm/processor.h
@@ -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__
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -654,10 +654,10 @@ int setup_arg_pages(struct linux_binprm
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)
--
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