| 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() |
| |
| From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> |
| |
| commit 903f9db10f18f735e62ba447147b6c434b6af003 upstream. |
| |
| 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 <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(-) |
| |
| --- a/drivers/tty/tty_io.c |
| +++ b/drivers/tty/tty_io.c |
| @@ -3154,7 +3154,10 @@ struct tty_struct *alloc_tty_struct(stru |
| |
| 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); |
| --- a/drivers/tty/tty_ldisc.c |
| +++ b/drivers/tty/tty_ldisc.c |
| @@ -804,12 +804,13 @@ void tty_ldisc_release(struct tty_struct |
| * 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; |
| } |
| |
| /** |
| --- a/include/linux/tty.h |
| +++ b/include/linux/tty.h |
| @@ -586,7 +586,7 @@ 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); |
| |