commit 7bbf1373e228840bb0295a2ca26d548ef37f448e
author Kees Cook <keescook@chromium.org> Tue May 01 15:19:04 2018 -0700
committer Thomas Gleixner <tglx@linutronix.de> Thu May 03 13:55:51 2018 +0200
tree b03e2356ba64fa645695440d0519324c43f365aa
parent a73ec77ee17ec556fe7f165d00314cb7c047b1ac

nospec: Allow getting/setting on non-current task

Adjust arch_prctl_get/set_spec_ctrl() to operate on tasks other than
current.

This is needed both for /proc/$pid/status queries and for seccomp (since
thread-syncing can trigger seccomp in non-current threads).

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/sys.c

diff --git a/kernel/sys.c b/kernel/sys.c
index b76dee2..b0eee41 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -2244,12 +2244,13 @@ static int propagate_has_child_subreaper(struct task_struct *p, void *data)
 	return 1;
 }
 
-int __weak arch_prctl_spec_ctrl_get(unsigned long which)
+int __weak arch_prctl_spec_ctrl_get(struct task_struct *t, unsigned long which)
 {
 	return -EINVAL;
 }
 
-int __weak arch_prctl_spec_ctrl_set(unsigned long which, unsigned long ctrl)
+int __weak arch_prctl_spec_ctrl_set(struct task_struct *t, unsigned long which,
+				    unsigned long ctrl)
 {
 	return -EINVAL;
 }
@@ -2465,12 +2466,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 	case PR_GET_SPECULATION_CTRL:
 		if (arg3 || arg4 || arg5)
 			return -EINVAL;
-		error = arch_prctl_spec_ctrl_get(arg2);
+		error = arch_prctl_spec_ctrl_get(me, arg2);
 		break;
 	case PR_SET_SPECULATION_CTRL:
 		if (arg4 || arg5)
 			return -EINVAL;
-		error = arch_prctl_spec_ctrl_set(arg2, arg3);
+		error = arch_prctl_spec_ctrl_set(me, arg2, arg3);
 		break;
 	default:
 		error = -EINVAL;