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-rw-r--r--mm/mremap.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/mm/mremap.c b/mm/mremap.c
index 1de98d4..a7c1f9f 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -277,9 +277,16 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,
if (old_len > vma->vm_end - addr)
goto Efault;
- if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {
- if (new_len > old_len)
+ /* Need to be careful about a growing mapping */
+ if (new_len > old_len) {
+ unsigned long pgoff;
+
+ if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP))
goto Efault;
+ pgoff = (addr - vma->vm_start) >> PAGE_SHIFT;
+ pgoff += vma->vm_pgoff;
+ if (pgoff + (new_len >> PAGE_SHIFT) < pgoff)
+ goto Einval;
}
if (vma->vm_flags & VM_LOCKED) {
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