This is a note to let you know that I've just added the patch titled

tty: Don't call panic() at tty_ldisc_init()

to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 903f9db10f18f735e62ba447147b6c434b6af003 Mon Sep 17 00:00:00 2001

From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Date: Thu, 5 Apr 2018 19:40:16 +0900 Subject: 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=883431818e036ae6a9981156a64b821110f3918...

Signed-off-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Reported-by: syzbot 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: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/tty_io.c | 5 ++++- drivers/tty/tty_ldisc.c | 5 +++-- include/linux/tty.h | 2 +- 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index 63114ea35ec1..7c838b90a31d 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -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); diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index c1cf6cb83185..8a88a7787cfe 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -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; }

/** diff --git a/include/linux/tty.h b/include/linux/tty.h index 47f8af22f216..1dd587ba6d88 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -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);