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 EB469C4332F for ; Mon, 16 May 2022 20:32:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345277AbiEPUcz (ORCPT ); Mon, 16 May 2022 16:32:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57592 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351032AbiEPUB4 (ORCPT ); Mon, 16 May 2022 16:01:56 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 539CD4756D; Mon, 16 May 2022 12:56:58 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id F18D1B81614; Mon, 16 May 2022 19:56:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4CCBAC385AA; Mon, 16 May 2022 19:56:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1652731015; bh=YEvJ+Z90ycumJC//xjiXZMSrJLry2O8DQ9GmHtH8Ezc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1PRq9D+MhfEkatl5TWO7P4ISkpXHkVwlnDCzvXlS+11U4/Fzc4wFnuAYMG+nnh2tD z0hku95xGV4LzdXW2ILJHY+Xa+8LsvcPXB5qmp/cuHvE/5f0rbFA70KA938jFmnJ+4 kalcqGbv1HTb0SMokvjRwF1xc62rdXkGltswkgVs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Starke Subject: [PATCH 5.17 076/114] tty: n_gsm: fix buffer over-read in gsm_dlci_data() Date: Mon, 16 May 2022 21:36:50 +0200 Message-Id: <20220516193627.669854974@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220516193625.489108457@linuxfoundation.org> References: <20220516193625.489108457@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Daniel Starke commit fd442e5ba30aaa75ea47b32149e7a3110dc20a46 upstream. 'len' is decreased after each octet that has its EA bit set to 0, which means that the value is encoded with additional octets. However, the final octet does not decreases 'len' which results in 'len' being one byte too long. A buffer over-read may occur in tty_insert_flip_string() as it tries to read one byte more than the passed content size of 'data'. Decrease 'len' also for the final octet which has the EA bit set to 1 to write the correct number of bytes from the internal receive buffer to the virtual tty. Fixes: 2e124b4a390c ("TTY: switch tty_flip_buffer_push") Cc: stable@vger.kernel.org Signed-off-by: Daniel Starke Link: https://lore.kernel.org/r/20220504081733.3494-1-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_gsm.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1658,6 +1658,7 @@ static void gsm_dlci_data(struct gsm_dlc if (len == 0) return; } + len--; slen++; tty = tty_port_tty_get(port); if (tty) {