[PATCH] ELF: warn if process starts with executable stack

[Alexey Dobriyan <adobriyan@xxxxxxxxx>]

PT_GNU_STACK is fail open design, at least warn people that something
isn't right.

Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
---

 fs/exec.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/fs/exec.c
+++ b/fs/exec.c
@@ -762,6 +762,13 @@ int setup_arg_pages(struct linux_binprm *bprm,
 		goto out_unlock;
 	BUG_ON(prev != vma);
 
+#ifdef CONFIG_MMU
+	if (vm_flags & VM_EXEC) {
+		pr_warn_once("process '%s'/%u started with executable stack\n",
+			     current->comm, current->pid);
+	}
+#endif
+
 	/* Move stack pages down in memory. */
 	if (stack_shift) {
 		ret = shift_arg_pages(vma, stack_shift);