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Commit 903f9db1 authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Greg Kroah-Hartman
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tty: Don't call panic() at tty_ldisc_init() 

syzbot is reporting kernel panic [1] triggered by memory allocation failure
at tty_ldisc_get() from tty_ldisc_init(). But since both tty_ldisc_get()
and caller of tty_ldisc_init() can cleanly handle errors, tty_ldisc_init()
does not need to call panic() when tty_ldisc_get() failed.

[1] https://syzkaller.appspot.com/bug?id=883431818e036ae6a9981156a64b821110f39187



Signed-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: default avatarsyzbot <syzkaller@googlegroups.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 598c2d41

drivers/tty/tty_io.c

+4 −1
Original line number Diff line number Diff line
@@ -2816,7 +2816,10 @@ struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx) 


	kref_init(&tty->kref);

	tty->magic = TTY_MAGIC;

	tty_ldisc_init(tty);

	if (tty_ldisc_init(tty)) {

		kfree(tty);

		return NULL;

	}

	tty->session = NULL;

	tty->pgrp = NULL;

	mutex_init(&tty->legacy_mutex);

drivers/tty/tty_ldisc.c

+3 −2
Original line number Diff line number Diff line
@@ -821,12 +821,13 @@ EXPORT_SYMBOL_GPL(tty_ldisc_release); 
 *	the tty structure is not completely set up when this call is made.

 */



void tty_ldisc_init(struct tty_struct *tty)

int tty_ldisc_init(struct tty_struct *tty)

{

	struct tty_ldisc *ld = tty_ldisc_get(tty, N_TTY);

	if (IS_ERR(ld))

		panic("n_tty: init_tty");

		return PTR_ERR(ld);

	tty->ldisc = ld;

	return 0;

}



/**

include/linux/tty.h

+1 −1
Original line number Diff line number Diff line
@@ -701,7 +701,7 @@ extern int tty_unregister_ldisc(int disc); 
extern int tty_set_ldisc(struct tty_struct *tty, int disc);

extern int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty);

extern void tty_ldisc_release(struct tty_struct *tty);

extern void tty_ldisc_init(struct tty_struct *tty);

extern int __must_check tty_ldisc_init(struct tty_struct *tty);

extern void tty_ldisc_deinit(struct tty_struct *tty);

extern int tty_ldisc_receive_buf(struct tty_ldisc *ld, const unsigned char *p,

				 char *f, int count);