strlcpy() reads the entire source buffer first. This read may exceed the destination size limit if a source string is not NUL-terminated [1]. The copy_to_user() call uses @len returned from strlcpy() directly without checking its value. This could potentially lead to read overflow. In an effort to remove strlcpy() completely [2], replace strlcpy() here with strscpy(). [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [2] https://github.com/KSPP/linux/issues/89 Signed-off-by: Azeem Shaikh <azeemshaikh38@xxxxxxxxx> --- drivers/tty/vt/keyboard.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c index 358f216c6cd6..15359c328a23 100644 --- a/drivers/tty/vt/keyboard.c +++ b/drivers/tty/vt/keyboard.c @@ -2079,12 +2079,15 @@ int vt_do_kdgkb_ioctl(int cmd, struct kbsentry __user *user_kdgkb, int perm) return -ENOMEM; spin_lock_irqsave(&func_buf_lock, flags); - len = strlcpy(kbs, func_table[kb_func] ? : "", len); + len = strscpy(kbs, func_table[kb_func] ? : "", len); spin_unlock_irqrestore(&func_buf_lock, flags); + if (len < 0) { + ret = -EFAULT; + break; + } ret = copy_to_user(user_kdgkb->kb_string, kbs, len + 1) ? -EFAULT : 0; - break; } case KDSKBSENT: -- 2.42.0.rc2.253.gd59a3bf2b4-goog
