Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757427Ab1CaMLX (ORCPT ); Thu, 31 Mar 2011 08:11:23 -0400 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:40792 "EHLO www.etchedpixels.co.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751552Ab1CaMLU (ORCPT ); Thu, 31 Mar 2011 08:11:20 -0400 Date: Thu, 31 Mar 2011 13:11:44 +0100 From: Alan Cox To: Mikhail Kshevetskiy Cc: linux-serial@vger.kernel.org, Greg Kroah-Hartman , stable@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] tty/n_gsm: fix bug in CRC calculation for gsm1 mode Message-ID: <20110331131144.74a579db@lxorguk.ukuu.org.uk> In-Reply-To: <1301184300-9158-1-git-send-email-mikhail.kshevetskiy@gmail.com> References: <1301184300-9158-1-git-send-email-mikhail.kshevetskiy@gmail.com> X-Mailer: Claws Mail 3.7.8 (GTK+ 2.22.0; x86_64-redhat-linux-gnu) Face: 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 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1115 Lines: 28 On Sun, 27 Mar 2011 04:05:00 +0400 Mikhail Kshevetskiy wrote: > Problem description: > gsm_queue() calculate a CRC for arrived frames. As a last step of > CRC calculation it call > > gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs); > > This work perfectly for the case of GSM0 mode as gsm->received_fcs > contain the last piece of data required to generate final CRC. > > gsm->received_fcs is not used for GSM1 mode. Thus we put an > additional byte to CRC calculation. As result we get a wrong CRC > and reject incoming frame. > > Signed-off-by: Mikhail Kshevetskiy Acked-by: Alan Cox (This wants cleaning up better as Mikhael also says but this patch is clear and unlike a big clean up a better base point for a stable fix and can be reworked further) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/