[PATCH] tty: vt: keyboard: do not copy an extra-byte in copy_to_user
From: Ajay Garg <hidden>
Date: 2021-11-06 09:21:01
Also in:
lkml
Subsystem:
the rest, tty layer and serial drivers · Maintainers:
Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
Both (statically-allocated) "user_kdgkb->kb_string" and (dynamically-allocated) "kbs" are of length "len", so we must not copy more than "len" bytes. Signed-off-by: Ajay Garg <redacted> --- drivers/tty/vt/keyboard.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index c7fbbcdcc346..dfef7de8a057 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c@@ -2070,7 +2070,7 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm) len = strlcpy(kbs, func_table[kb_func] ? : "", len); spin_unlock_irqrestore(&func_buf_lock, flags); - ret = copy_to_user(user_kdgkb->kb_string, kbs, len + 1) ? + ret = copy_to_user(user_kdgkb->kb_string, kbs, len) ? -EFAULT : 0; break;
--
2.30.2