--- mm/memory.c
+++ mm/memory.c
@@ -1282,10 +1282,20 @@ int __get_user_pages(struct task_struct
return i ? : -EFAULT;
}
if (pages) {
- struct page *page = vm_normal_page(gate_vma, start, *pte);
+ struct page *page;
+
+ page = vm_normal_page(gate_vma, start, *pte);
+ if (!page) {
+ if (!(gup_flags & FOLL_DUMP) &&
+ is_zero_pfn(pte_pfn(*pte)))
+ page = pte_page(*pte);
+ else {
+ pte_unmap(pte);
+ return i ? : -EFAULT;
+ }
+ }
pages[i] = page;
- if (page)
- get_page(page);
+ get_page(page);
}
pte_unmap(pte);
if (vmas)
@@ -2620,6 +2630,40 @@ out_release:
}
/*
+ * 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.
+ */
+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) {
+ struct vm_area_struct *prev = vma->vm_prev;
+
+ /*
+ * Is there a mapping abutting this one below?
+ *
+ * That's only ok if it's the same stack mapping
+ * that has gotten split..
+ */
+ if (prev && prev->vm_end == address)
+ return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
+
+ expand_stack(vma, address - PAGE_SIZE);
+ }
+ if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
+ struct vm_area_struct *next = vma->vm_next;
+
+ /* As VM_GROWSDOWN but s/below/above/ */
+ if (next && next->vm_start == address + PAGE_SIZE)
+ return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
+
+ expand_upwards(vma, address + PAGE_SIZE);
+ }
+ return 0;
+}
+
+/*
* We enter with non-exclusive mmap_sem (to exclude vma changes,
* but allow concurrent faults), and pte mapped but not yet locked.
* We return with mmap_sem still held, but pte unmapped and unlocked.
@@ -2632,19 +2676,23 @@ static int do_anonymous_page(struct mm_s
spinlock_t *ptl;
pte_t entry;
+ pte_unmap(page_table);
+
+ /* Check if we need to add a guard page to the stack */
+ if (check_stack_guard_page(vma, address) < 0)
+ return VM_FAULT_SIGBUS;
+
+ /* Use the zero-page for reads */
if (!(flags & FAULT_FLAG_WRITE)) {
entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
vma->vm_page_prot));
- ptl = pte_lockptr(mm, pmd);
- spin_lock(ptl);
+ page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
if (!pte_none(*page_table))
goto unlock;
goto setpte;
}
/* Allocate our own private page. */
- pte_unmap(page_table);
-
if (unlikely(anon_vma_prepare(vma)))
goto oom;
page = alloc_zeroed_user_highpage_movable(vma, address);
projects / ziggy471-frankenstein-kernel.git / blobdiff