From db5f7d04fd718b94f428220b2ba4d4c87f55a3a5 Mon Sep 17 00:00:00 2001 From: James Hogan Date: Tue, 13 May 2014 23:58:24 +0100 Subject: [PATCH] metag: Reduce maximum stack size to 256MB 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 Cc: Helge Deller Cc: "James E.J. Bottomley" Cc: linux-parisc@vger.kernel.org Cc: linux-metag@vger.kernel.org Cc: John David Anglin Signed-off-by: Greg Kroah-Hartman --- 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(-) diff --git a/arch/metag/include/asm/processor.h b/arch/metag/include/asm/processor.h index f16477d..3be8581 100644 --- 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. diff --git a/arch/parisc/include/asm/processor.h b/arch/parisc/include/asm/processor.h index 198a86f..86522ef 100644 --- 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__ diff --git a/fs/exec.c b/fs/exec.c index 3d78fcc..31e46b1 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -654,10 +654,10 @@ 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) -- 2.7.4