Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
mm: make the mlock() stack guard page checks stricter
If we've split the stack vma, only the lowest one has the guard page.
Now that we have a doubly linked list of vma's, checking this is trivial.
Tested-by: Ian Campbell <ijc@hellion.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+16
-5
+16
-5
mm/mlock.c
+16
-5
mm/mlock.c
···
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}
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}
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+
/* Is the vma a continuation of the stack vma above it? */
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+
static inline int vma_stack_continue(struct vm_area_struct *vma, unsigned long addr)
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{
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return vma && (vma->vm_end == addr) && (vma->vm_flags & VM_GROWSDOWN);
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}
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+
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static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
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{
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return (vma->vm_flags & VM_GROWSDOWN) &&
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(vma->vm_start == addr) &&
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!vma_stack_continue(vma->vm_prev, addr);
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}
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+
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/**
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* __mlock_vma_pages_range() - mlock a range of pages in the vma.
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* @vma: target vma
···
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gup_flags |= FOLL_WRITE;
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/* We don't try to access the guard page of a stack vma */
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-
if (vma->vm_flags & VM_GROWSDOWN) {
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-
if (start == vma->vm_start) {
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-
start += PAGE_SIZE;
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-
nr_pages--;
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-
}
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+
if (stack_guard_page(vma, start)) {
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addr += PAGE_SIZE;
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nr_pages--;
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}
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while (nr_pages > 0) {