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Defer funsetown() calls for a TTY to tty_rel_free().

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We were otherwise failing to call funsetown() for some descriptors
associated with a tty, such as pts descriptors.  Then, if the
descriptor is closed before the owner exits, we may get memory
corruption.

Reported by:	syzbot+c9b6206303bf47bac87e@syzkaller.appspotmail.com
Reviewed by:	ed
MFC after:	3 days
Sponsored by:	The FreeBSD Foundation
This commit is contained in:
Mark Johnston 2019-07-04 15:42:02 +00:00
parent 17f1623d42
commit 6a01874c5a
1 changed files with 3 additions and 3 deletions
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6
sys/kern/tty.c
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@ -238,9 +238,6 @@ ttydev_leave(struct tty *tp)
tp->t_flags |= TF_OPENCLOSE;
/* Stop asynchronous I/O. */
funsetown(&tp->t_sigio);
/* Remove console TTY. */
if (constty == tp)
constty_clear();
@ -1134,6 +1131,9 @@ tty_rel_free(struct tty *tp)
return;
}
/* Stop asynchronous I/O. */
funsetown(&tp->t_sigio);
/* TTY can be deallocated. */
dev = tp->t_dev;
tp->t_dev = NULL;