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

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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>
This commit is contained in:
Tetsuo Handa 2018-04-05 19:40:16 +09:00 committed by Greg Kroah-Hartman
parent c0ed8ece4e
commit 4854b9665c
3 changed files with 8 additions and 4 deletions
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5
drivers/tty/tty_io.c
View File

@ -2815,7 +2815,10 @@ 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);

5
drivers/tty/tty_ldisc.c
View File

@ -823,12 +823,13 @@ 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;
}
/**

2
include/linux/tty.h
View File

@ -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);