[PATCH] Restrict stack space reservation to rlimit
Michael Neuling
mikey at neuling.org
Mon Feb 8 11:07:52 EST 2010
apkm, linus: this or something like it needs to go into 2.6.33 (& 32) to
fix 'ulimit -s'.
Mikey
[PATCH] Restrict stack space reservation to rlimit
When reserving stack space for a new process, make sure we're not
attempting to allocate more than rlimit allows.
Also, reserve the same stack size independent of page size.
This fixes a bug unmasked by fc63cf237078c86214abcb2ee9926d8ad289da9b
Signed-off-by: Michael Neuling <mikey at neuling.org>
Cc: Anton Blanchard <anton at samba.org>
Cc: stable at kernel.org
---
fs/exec.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
Index: clone1/fs/exec.c
===================================================================
--- clone1.orig/fs/exec.c
+++ clone1/fs/exec.c
@@ -554,7 +554,7 @@ static int shift_arg_pages(struct vm_are
return 0;
}
-#define EXTRA_STACK_VM_PAGES 20 /* random */
+#define EXTRA_STACK_VM_SIZE 81920UL /* randomly 20 4K pages */
/*
* Finalizes the stack vm_area_struct. The flags and permissions are updated,
@@ -627,10 +627,13 @@ int setup_arg_pages(struct linux_binprm
goto out_unlock;
}
+ stack_base = min(EXTRA_STACK_VM_SIZE,
+ current->signal->rlim[RLIMIT_STACK].rlim_cur) -
+ PAGE_SIZE;
#ifdef CONFIG_STACK_GROWSUP
- stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
+ stack_base = vma->vm_end + stack_base;
#else
- stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
+ stack_base = vma->vm_start - stack_base;
#endif
ret = expand_stack(vma, stack_base);
if (ret)
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