compat: use scoped user access in get_compat_sigevent()

ae78eff3 · Linus Torvalds <[email protected]> · 2026-10-19 19:23:18 -10:00

get_compat_sigevent() does one access_ok() on the user structure and
then reads four fields with __get_user().  Each of those reads enables
and disables user access on its own, so the single range check no longer
buys anything.

Read the fields inside a scoped_user_read_access() instead.

This is part of getting rid of __get_user() and __put_user() entirely.

Signed-off-by: Linus Torvalds <[email protected]>

Commit: ae78eff333746326e630e505d7fac0d237e644ef
Parents: b040da2a

Changes

1 files changed · +12 −8

File	Status	Add	Del	Content
kernel/compat.c	modified	+12	−8	View file

kernel/compat.c

View file

diff --git a/kernel/compat.c b/kernel/compat.c
index fb50f29..c754793 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -180,14 +180,18 @@ int get_compat_sigevent(struct sigevent *event,
 		const struct compat_sigevent __user *u_event)
 {
 	memset(event, 0, sizeof(*event));
-	return (!access_ok(u_event, sizeof(*u_event)) ||
-		__get_user(event->sigev_value.sival_int,
-			&u_event->sigev_value.sival_int) ||
-		__get_user(event->sigev_signo, &u_event->sigev_signo) ||
-		__get_user(event->sigev_notify, &u_event->sigev_notify) ||
-		__get_user(event->sigev_notify_thread_id,
-			&u_event->sigev_notify_thread_id))
-		? -EFAULT : 0;
+	scoped_user_read_access(u_event, Efault) {
+		unsafe_get_user(event->sigev_value.sival_int,
+				&u_event->sigev_value.sival_int, Efault);
+		unsafe_get_user(event->sigev_signo, &u_event->sigev_signo, Efault);
+		unsafe_get_user(event->sigev_notify, &u_event->sigev_notify, Efault);
+		unsafe_get_user(event->sigev_notify_thread_id,
+				&u_event->sigev_notify_thread_id, Efault);
+	}
+	return 0;
+
+Efault:
+	return -EFAULT;
 }
 
 long compat_get_bitmap(unsigned long *mask, const compat_ulong_t __user *umask,