This is a note to let you know that I've just added the patch titled
tty/n_gsm: fix bug in CRC calculation for gsm1 mode
to the 2.6.38-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tty-n_gsm-fix-bug-in-crc-calculation-for-gsm1-mode.patch
and it can be found in the queue-2.6.38 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 9db4e4381a8e881ff65a5d3400bfa471f84217e7 Mon Sep 17 00:00:00 2001
From: Mikhail Kshevetskiy <[email protected]>
Date: Sun, 27 Mar 2011 04:05:00 +0400
Subject: tty/n_gsm: fix bug in CRC calculation for gsm1 mode
From: Mikhail Kshevetskiy <[email protected]>
commit 9db4e4381a8e881ff65a5d3400bfa471f84217e7 upstream.
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 <[email protected]>
Acked-by: Alan Cox <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/tty/n_gsm.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1659,8 +1659,12 @@ static void gsm_queue(struct gsm_mux *gs
if ((gsm->control & ~PF) == UI)
gsm->fcs = gsm_fcs_add_block(gsm->fcs, gsm->buf, gsm->len);
- /* generate final CRC with received FCS */
- gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs);
+ if (gsm->encoding == 0){
+ /* WARNING: gsm->received_fcs is used for gsm->encoding = 0
only.
+ In this case it contain the last piece of data
+ required to generate final CRC */
+ gsm->fcs = gsm_fcs_add(gsm->fcs, gsm->received_fcs);
+ }
if (gsm->fcs != GOOD_FCS) {
gsm->bad_fcs++;
if (debug & 4)
Patches currently in stable-queue which might be from
[email protected] are
queue-2.6.38/tty-n_gsm-fix-bug-in-crc-calculation-for-gsm1-mode.patch
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