From: Richard Weinberger <richard@nod.at>
Date: Sun, 12 May 2013 21:26:03 +0000 (+0200)
Subject: um: Mark stub pages mapping with VM_PFNMAP
X-Git-Tag: firefly_0821_release~176^2~5667^2~4
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=dee20035b42d569984d2c16041b51e4d75e233b5;p=firefly-linux-kernel-4.4.55.git

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 ff03067a3b14..007d5503f49b 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -123,7 +123,7 @@ void uml_setup_stubs(struct mm_struct *mm)
 	/* 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);