From: Richard Weinberger <richard@nod.at>
Date: Sun, 20 Jul 2014 11:09:15 +0000 (+0200)
Subject: um: Ensure that a stub page cannot get unmapped
X-Git-Tag: v3.16-rc6~6^2~2
X-Git-Url: http://git.cascardo.info/?a=commitdiff_plain;h=284e6d39516cc7f9fbceebb259849fcb41559a7b;p=cascardo%2Flinux.git

um: Ensure that a stub page cannot get unmapped

Trinity discovered an execution path such that a task
can unmap his stub page.

Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
---

diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
index 9472079471bb..1fc619e5dfe9 100644
--- a/arch/um/kernel/tlb.c
+++ b/arch/um/kernel/tlb.c
@@ -124,6 +124,9 @@ static int add_munmap(unsigned long addr, unsigned long len,
 	struct host_vm_op *last;
 	int ret = 0;
 
+	if ((addr >= STUB_START) && (addr < STUB_END))
+		return -EINVAL;
+
 	if (hvc->index != 0) {
 		last = &hvc->ops[hvc->index - 1];
 		if ((last->type == MUNMAP) &&