diff options
| author | Mikhail Kshevetskiy <mikhail.kshevetskiy@gmail.com> | 2011-03-27 04:05:00 +0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-05-02 09:19:38 -0700 |
| commit | 7b394b6f584438e9048825dd4571299945ce9b54 (patch) | |
| tree | 9a706d5295ab57cef0d4403638a6eeca987f9933 /drivers/tty | |
| parent | 60edc65d5d2c1b61d20f28b70b3ac5140dc82f6a (diff) | |
tty/n_gsm: fix bug in CRC calculation for gsm1 mode
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 <mikhail.kshevetskiy@gmail.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/n_gsm.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index aa2e5d3eb01..c4b0ef1a387 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -1659,8 +1659,12 @@ static void gsm_queue(struct gsm_mux *gsm) 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) |