From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_HIGH,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 874AEC46469 for ; Tue, 11 Sep 2018 01:48:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0B12B20645 for ; Tue, 11 Sep 2018 01:48:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=arista.com header.i=@arista.com header.b="ogL2jtZY" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0B12B20645 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=arista.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726941AbeIKGpV (ORCPT ); Tue, 11 Sep 2018 02:45:21 -0400 Received: from mail-ed1-f65.google.com ([209.85.208.65]:34089 "EHLO mail-ed1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726562AbeIKGpU (ORCPT ); Tue, 11 Sep 2018 02:45:20 -0400 Received: by mail-ed1-f65.google.com with SMTP id u1-v6so17996911eds.1 for ; Mon, 10 Sep 2018 18:48:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=googlenew; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=pr975JCzWCkcuM69evolnKQNNRXCXUiPHrsc4GObTkU=; b=ogL2jtZY5fj1Zggr2N/4zNGOqM0z+JWsyFzDADitnz9ei8XQm5sQ/jF9RUbxf0y/lG PB35uO23nc7WG7ytYd+E467l3mWpaJXK0OtsXsOk5LKxEJFduTTUb5MUEvPNa/En39Fq ujUuw/zkh2X3rsUnGJaKKhaSRCHQBUAaWpoufnkfn88p48QwdGdkhXAAiPP1S86rOT45 LzgB8GydICrqnUcIWjf4ECJ5etYhqO47yfS8/NkJYtR3ohJzBnhh2j4AMqsPeIiZFfpK H07Ysh4jn+3AQoay7Ydf2SMIZFNeJCqX/a1SezZsIBf836MKG+G+1eRwbHAw1kqu9M7V u9HA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=pr975JCzWCkcuM69evolnKQNNRXCXUiPHrsc4GObTkU=; b=uJqeHzBEcnEJq/RScfgxI5m0w9NWHp0+PFCNpx3SPf3tHOz3RdG+3KIrhXwGEOGOzc 3NJ6dhHYpSheg3u6QS2YWvg1NddSbsihbZ4u5oStaf/vYwMzgCp9SJM2vETFrzmBFCwb q8smelv0H0AULr9bOzJP1bl4jGM9Rs7HbRlviLgWBN7kRtPHuay9enwZtkQuogAgaJIe lntUFrrJ1kOkNzNihwQW12TKBUXxv7xjMu3N/pX2OXfzWs43AUS8q9AfV2kUR0+r8rPg NDAhuBRTYqBhSRoM5EG0gskKBvr6d5pCEANEj7WMYKfidIVtXDqBdXWWZtU765cKE65/ WUzQ== X-Gm-Message-State: APzg51AMB8PMWyqEq3emkFl0goPhUa8/pMf9XbhBg0s2hidBQAidLYTf oYDWhoRjdd0lGmJZ35WnlvcOk7hER9Q= X-Google-Smtp-Source: ANB0VdbUINPhHHCXk2+wyR61+kDmYILqf+Gvam9fl65YnED6Ak5YO/9Dgdm8UZx4y9esIkEGnXR3Yw== X-Received: by 2002:a50:a2e5:: with SMTP id 92-v6mr24532781edm.106.1536630509095; Mon, 10 Sep 2018 18:48:29 -0700 (PDT) Received: from dhcp.ire.aristanetworks.com ([217.173.96.166]) by smtp.gmail.com with ESMTPSA id x22-v6sm9171002edb.8.2018.09.10.18.48.27 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 10 Sep 2018 18:48:28 -0700 (PDT) From: Dmitry Safonov To: linux-kernel@vger.kernel.org Cc: Dmitry Safonov <0x7f454c46@gmail.com>, Dmitry Safonov , Daniel Axtens , Dmitry Vyukov , Michael Neuling , Mikulas Patocka , Nathan March , =?UTF-8?q?Pasi=20K=C3=A4rkk=C3=A4inen?= , Peter Hurley , "Rong, Chen" , Sergey Senozhatsky , Tan Xiaojun , Tetsuo Handa , Greg Kroah-Hartman , Jiri Slaby Subject: [PATCHv3 4/6] tty/lockdep: Add ldisc_sem asserts Date: Tue, 11 Sep 2018 02:48:19 +0100 Message-Id: <20180911014821.26286-5-dima@arista.com> X-Mailer: git-send-email 2.13.6 In-Reply-To: <20180911014821.26286-1-dima@arista.com> References: <20180911014821.26286-1-dima@arista.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Make sure under CONFIG_LOCKDEP that each change to line discipline is done with held write semaphor. Otherwise potential reader will have a good time dereferencing incomplete/uninitialized ldisc. Exception here is tty_ldisc_open(), as it's called without ldisc_sem locked by tty_init_dev() for the tty->link. Cc: Greg Kroah-Hartman Cc: Jiri Slaby Signed-off-by: Dmitry Safonov --- drivers/tty/tty_ldisc.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index fc4c97cae01e..202cb645582f 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -471,6 +471,7 @@ static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) { + lockdep_assert_held(&tty->ldisc_sem); WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); clear_bit(TTY_LDISC_OPEN, &tty->flags); if (ld->ops->close) @@ -492,6 +493,7 @@ static int tty_ldisc_failto(struct tty_struct *tty, int ld) struct tty_ldisc *disc = tty_ldisc_get(tty, ld); int r; + lockdep_assert_held(&tty->ldisc_sem); if (IS_ERR(disc)) return PTR_ERR(disc); tty->ldisc = disc; @@ -615,6 +617,7 @@ EXPORT_SYMBOL_GPL(tty_set_ldisc); */ static void tty_ldisc_kill(struct tty_struct *tty) { + lockdep_assert_held(&tty->ldisc_sem); if (!tty->ldisc) return; /* @@ -662,6 +665,7 @@ int tty_ldisc_reinit(struct tty_struct *tty, int disc) struct tty_ldisc *ld; int retval; + lockdep_assert_held(&tty->ldisc_sem); ld = tty_ldisc_get(tty, disc); if (IS_ERR(ld)) { BUG_ON(disc == N_TTY); @@ -825,6 +829,7 @@ int tty_ldisc_init(struct tty_struct *tty) */ void tty_ldisc_deinit(struct tty_struct *tty) { + /* no ldisc_sem, tty is being destroyed */ if (tty->ldisc) tty_ldisc_put(tty->ldisc); tty->ldisc = NULL; -- 2.13.6