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Commit 2ea81868 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Linus Torvalds
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[PATCH] tty: fix the locking for signal->session in disassociate_ctty 



commit 24ec839c while fixing the locking for
signal->tty got the locking wrong for signal->session.  This places our
accesses of signal->session back under the tasklist_lock where they belong.

Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 680a9671

drivers/char/tty_io.c

+1 −3
Original line number Diff line number Diff line
@@ -1496,7 +1496,6 @@ void disassociate_ctty(int on_exit) 
{

	struct tty_struct *tty;

	int tty_pgrp = -1;

	int session;



	lock_kernel();
@@ -1530,7 +1529,6 @@ void disassociate_ctty(int on_exit) 


	spin_lock_irq(&current->sighand->siglock);

	current->signal->tty_old_pgrp = 0;

	session = process_session(current);

	spin_unlock_irq(&current->sighand->siglock);



	mutex_lock(&tty_mutex);
@@ -1549,7 +1547,7 @@ void disassociate_ctty(int on_exit) 


	/* Now clear signal->tty under the lock */

	read_lock(&tasklist_lock);

	session_clear_tty(session);

	session_clear_tty(process_session(current));

	read_unlock(&tasklist_lock);

	unlock_kernel();

}