From 26834e6a6d4653db4bbb19a0bddf5a2620ea9c47 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Thu, 5 Apr 2018 19:40:16 +0900 Subject: [PATCH] tty: Don't call panic() at tty_ldisc_init() [ Upstream commit 903f9db10f18f735e62ba447147b6c434b6af003 ] 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: Tetsuo Handa Reported-by: syzbot Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: stable Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- 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 483757d7505e7..152cd369ce842 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -3160,7 +3160,10 @@ 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 3737f55272d2c..7e675acd9cbcb 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -800,12 +800,13 @@ void tty_ldisc_release(struct tty_struct *tty) * 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 5ed0055088483..0d56f919bda3e 100644 --- a/include/linux/tty.h +++ b/include/linux/tty.h @@ -582,7 +582,7 @@ extern int tty_unregister_ldisc(int disc); extern int tty_set_ldisc(struct tty_struct *tty, int ldisc); 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 void tty_ldisc_begin(void); -- 2.50.1