um: Mark stub pages mapping with VM_PFNMAP
Ensure that a process cannot destroy his stub pages with
using MADV_DONTNEED and friends.
Reported-by: toralf.foerster@gmx.de
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index ff03067..007d550 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -123,7 +123,7 @@
/* dup_mmap already holds mmap_sem */
err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
VM_READ | VM_MAYREAD | VM_EXEC |
- VM_MAYEXEC | VM_DONTCOPY,
+ VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP,
mm->context.stub_pages);
if (err) {
printk(KERN_ERR "install_special_mapping returned %d\n", err);