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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD431C433F5 for ; Wed, 4 May 2022 08:19:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240091AbiEDIW5 (ORCPT ); Wed, 4 May 2022 04:22:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50658 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346330AbiEDIWp (ORCPT ); Wed, 4 May 2022 04:22:45 -0400 X-Greylist: delayed 62 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Wed, 04 May 2022 01:19:08 PDT Received: from mta-64-227.siemens.flowmailer.net (mta-64-227.siemens.flowmailer.net [185.136.64.227]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1A93322BEC for ; Wed, 4 May 2022 01:19:08 -0700 (PDT) Received: by mta-64-227.siemens.flowmailer.net with ESMTPSA id 202205040818047e1ff9d629ca237038 for ; Wed, 04 May 2022 10:18:05 +0200 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; s=fm1; d=siemens.com; i=daniel.starke@siemens.com; h=Date:From:Subject:To:Message-ID:MIME-Version:Content-Type:Content-Transfer-Encoding:Cc:References:In-Reply-To; bh=pAhSICUghL2Tdq7gJgyrM0AnGc3NFl9PMHLsjpLV0lg=; b=F3dffOSVez5dYK+lSZgubH5uaAJwwDy0kuPiCOJJ9/fzIxVXeR6pDvVYJdzwSYmVRRf4C/ 38bTz0xrAnfV80m6NBW22MfpjnOgdMoNq3+MD+e/Yet5byonFiKQBHDRGwm7V/mzPYldmOMR ZjVBAiqkeyXt5K9nC2PfxCKIISC7w=; From: "D. Starke" To: linux-serial@vger.kernel.org, gregkh@linuxfoundation.org, jirislaby@kernel.org Cc: linux-kernel@vger.kernel.org, Daniel Starke Subject: [PATCH 3/3] tty: n_gsm: fix invalid gsmtty_write_room() result Date: Wed, 4 May 2022 10:17:33 +0200 Message-Id: <20220504081733.3494-3-daniel.starke@siemens.com> In-Reply-To: <20220504081733.3494-1-daniel.starke@siemens.com> References: <20220504081733.3494-1-daniel.starke@siemens.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Flowmailer-Platform: Siemens Feedback-ID: 519:519-314044:519-21489:flowmailer Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Daniel Starke gsmtty_write() does not prevent the user to use the full fifo size of 4096 bytes as allocated in gsm_dlci_alloc(). However, gsmtty_write_room() tries to limit the return value by 'TX_SIZE' and returns a negative value if the fifo has more than 'TX_SIZE' bytes stored. This is obviously wrong as 'TX_SIZE' is defined as 512. Define 'TX_SIZE' to the fifo size and use it accordingly for allocation to keep the current behavior. Return the correct remaining size of the fifo in gsmtty_write_room() via kfifo_avail(). Fixes: e1eaea46bb40 ("tty: n_gsm line discipline") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke --- drivers/tty/n_gsm.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index bcb714031d69..fd8b86dde525 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -137,6 +137,7 @@ struct gsm_dlci { int retries; /* Uplink tty if active */ struct tty_port port; /* The tty bound to this DLCI if there is one */ +#define TX_SIZE 4096 /* Must be power of 2. */ struct kfifo fifo; /* Queue fifo for the DLCI */ int adaption; /* Adaption layer in use */ int prev_adaption; @@ -1731,7 +1732,7 @@ static struct gsm_dlci *gsm_dlci_alloc(struct gsm_mux *gsm, int addr) return NULL; spin_lock_init(&dlci->lock); mutex_init(&dlci->mutex); - if (kfifo_alloc(&dlci->fifo, 4096, GFP_KERNEL) < 0) { + if (kfifo_alloc(&dlci->fifo, TX_SIZE, GFP_KERNEL) < 0) { kfree(dlci); return NULL; } @@ -2976,8 +2977,6 @@ static struct tty_ldisc_ops tty_ldisc_packet = { * Virtual tty side */ -#define TX_SIZE 512 - /** * gsm_modem_upd_via_data - send modem bits via convergence layer * @dlci: channel @@ -3217,7 +3216,7 @@ static unsigned int gsmtty_write_room(struct tty_struct *tty) struct gsm_dlci *dlci = tty->driver_data; if (dlci->state == DLCI_CLOSED) return 0; - return TX_SIZE - kfifo_len(&dlci->fifo); + return kfifo_avail(&dlci->fifo); } static unsigned int gsmtty_chars_in_buffer(struct tty_struct *tty) -- 2.34.1