In commit 320b2b8de12698082609ebbc1a17165727f4c893
mm: keep a guard page below a grow-down stack segment
we prevented stacks from growing downwards into other vma areas.
But some arhictectures (ia64 and pa-risc) have stacks that
grow upwards. Provide the same protection for them.
Signed-off-by: Tony Luc <tony.luck@xxxxxxxxx>
---
Pointed out to me by Matthew Wilcox.
DANGER, DANGER - NOT TESTED on pa-risc yet DO NOT APPLY WITHOUT AN ACK FROM PA-RISC LAND!
Are there any other architectures with upward growing stacks?
diff --git a/mm/memory.c b/mm/memory.c
index b6e5fd2..9dcef72 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2760,21 +2760,35 @@ out_release:
}
/*
- * This is like a special single-page "expand_downwards()",
- * except we must first make sure that 'address-PAGE_SIZE'
+ * This is like a special single-page "expand_{down|up}wards()",
+ * except we must first make sure that 'address{-|+}PAGE_SIZE'
* doesn't hit another vma.
*
* The "find_vma()" will do the right thing even if we wrap
*/
static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
{
- address &= PAGE_MASK;
- if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
- address -= PAGE_SIZE;
- if (find_vma(vma->vm_mm, address) != vma)
- return -ENOMEM;
+ struct vm_area_struct *v;
+
+ if (vma->vm_flags & VM_GROWSDOWN) {
+ address &= PAGE_MASK;
+ if (address == vma->vm_start) {
+ address -= PAGE_SIZE;
+ if (find_vma(vma->vm_mm, address) != vma)
+ return -ENOMEM;
- expand_stack(vma, address);
+ expand_stack(vma, address);
+ }
+ } else if (vma->vm_flags & VM_GROWSUP) {
+ address = PAGE_ALIGN(address + 1);
+ if (address == vma->vm_end) {
+ address += PAGE_SIZE;
+ if ((v = find_vma(vma->vm_mm, address)) &&
+ v->vm_start <= address) {
+ return -ENOMEM;
+ }
+ expand_upwards(vma, address);
+ }
}
return 0;
}
--
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