From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751452AbWIDPNo (ORCPT ); Mon, 4 Sep 2006 11:13:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751459AbWIDPNn (ORCPT ); Mon, 4 Sep 2006 11:13:43 -0400 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:13474 "EHLO lxorguk.ukuu.org.uk") by vger.kernel.org with ESMTP id S1751452AbWIDPNn (ORCPT ); Mon, 4 Sep 2006 11:13:43 -0400 Subject: Re: [PATCH] audit/accounting: tty locking From: Alan Cox To: akpm@osdl.org Cc: linux-kernel@vger.kernel.org In-Reply-To: <1157380592.30801.94.camel@localhost.localdomain> References: <1157380592.30801.94.camel@localhost.localdomain> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Mon, 04 Sep 2006 16:36:19 +0100 Message-Id: <1157384179.30801.100.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.2 (2.6.2-1.fc5.5) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ar Llu, 2006-09-04 am 15:36 +0100, ysgrifennodd Alan Cox: > Fairly basic stuff .. make sure the name we are encoding doesn't vanish > under us. Here's a replacement that is more paranoid about the locking as suggested by Arjan. The whole current->signal-> locking is all deeply strange but its for someone else to sort out. Add rather than replace the lock for acct.c Signed-off-by: Alan Cox diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.18-rc5-mm1/kernel/acct.c linux-2.6.18-rc5-mm1/kernel/acct.c --- linux.vanilla-2.6.18-rc5-mm1/kernel/acct.c 2006-09-01 13:39:20.000000000 +0100 +++ linux-2.6.18-rc5-mm1/kernel/acct.c 2006-09-04 15:47:58.324205496 +0100 @@ -483,10 +483,14 @@ ac.ac_ppid = current->parent->tgid; #endif - read_lock(&tasklist_lock); /* pin current->signal */ + mutex_lock(&tty_mutex); + /* FIXME: Whoever is responsible for current->signal locking needs + to use the same locking all over the kernel and document it */ + read_lock(&tasklist_lock); ac.ac_tty = current->signal->tty ? old_encode_dev(tty_devnum(current->signal->tty)) : 0; read_unlock(&tasklist_lock); + mutex_unlock(&tty_mutex); spin_lock_irq(¤t->sighand->siglock); ac.ac_utime = encode_comp_t(jiffies_to_AHZ(cputime_to_jiffies(pacct->ac_utime))); diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla-2.6.18-rc5-mm1/kernel/auditsc.c linux-2.6.18-rc5-mm1/kernel/auditsc.c --- linux.vanilla-2.6.18-rc5-mm1/kernel/auditsc.c 2006-09-01 13:39:20.000000000 +0100 +++ linux-2.6.18-rc5-mm1/kernel/auditsc.c 2006-09-01 13:55:51.000000000 +0100 @@ -766,6 +766,8 @@ audit_log_format(ab, " success=%s exit=%ld", (context->return_valid==AUDITSC_SUCCESS)?"yes":"no", context->return_code); + + mutex_lock(&tty_mutex); if (tsk->signal && tsk->signal->tty && tsk->signal->tty->name) tty = tsk->signal->tty->name; else @@ -787,6 +789,9 @@ context->gid, context->euid, context->suid, context->fsuid, context->egid, context->sgid, context->fsgid, tty); + + mutex_unlock(&tty_mutex); + audit_log_task_info(ab, tsk); if (context->filterkey) { audit_log_format(ab, " key=");