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>
git-mirror · Jul 20, 2014 · 284e6d3 · 284e6d3
1 parent ae5db6d
commit 284e6d3
Showing 1 changed file with 3 additions and 0 deletions.
diff --git 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) &&