Commit 5acccdd8 authored by Yi Yang's avatar Yi Yang
Browse files

tty: vt device use only n_tty ldisc 

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IACT4T


CVE: CVE-2024-40966

--------------------------------

After backport mainline commit 6bd23e0c2bb6 ("tty: add the option to have
a tty reject a new ldisc") Introduced kabi breakage.
Fix kabi breakage by check whether it is vt device in tty_set_ldisc(), and
check ldisc whether it is N_TTY.

Fixes: 6bd23e0c2bb6 ("tty: add the option to have a tty reject a new ldisc")
Signed-off-by: default avatarYi Yang <yiyang13@huawei.com>
parent 5b0afd4b

drivers/tty/tty_ldisc.c

+7 −3
Original line number Diff line number Diff line
@@ -579,11 +579,15 @@ int tty_set_ldisc(struct tty_struct *tty, int disc) 
		goto out;

	}



	if (tty->ops->ldisc_ok) {

		retval = tty->ops->ldisc_ok(tty, disc);

		if (retval)

#ifdef CONFIG_VT

	/*vt device use only n_tty ldisc*/

	if (tty->ops->ioctl == vt_ioctl) {

		if (disc != N_TTY) {

			retval = -EINVAL;

			goto out;

		}

	}

#endif



	old_ldisc = tty->ldisc;

drivers/tty/vt/vt.c

+0 −10
Original line number Diff line number Diff line
@@ -3448,15 +3448,6 @@ static void con_cleanup(struct tty_struct *tty) 
	tty_port_put(&vc->port);

}



/*

 * We can't deal with anything but the N_TTY ldisc,

 * because we can sleep in our write() routine.

 */

static int con_ldisc_ok(struct tty_struct *tty, int ldisc)

{

	return ldisc == N_TTY ? 0 : -EINVAL;

}



static int default_color           = 7; /* white */

static int default_italic_color    = 2; // green (ASCII)

static int default_underline_color = 3; // cyan (ASCII)
@@ -3585,7 +3576,6 @@ static const struct tty_operations con_ops = { 
	.resize = vt_resize,

	.shutdown = con_shutdown,

	.cleanup = con_cleanup,

	.ldisc_ok = con_ldisc_ok,

};



static struct cdev vc0_cdev;

include/linux/tty_driver.h

+0 −1
Original line number Diff line number Diff line
@@ -256,7 +256,6 @@ struct tty_operations { 
		      const unsigned char *buf, int count);

	int  (*put_char)(struct tty_struct *tty, unsigned char ch);

	void (*flush_chars)(struct tty_struct *tty);

	int (*ldisc_ok)(struct tty_struct *tty, int ldisc);

	int  (*write_room)(struct tty_struct *tty);

	int  (*chars_in_buffer)(struct tty_struct *tty);

	int  (*ioctl)(struct tty_struct *tty,