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| author | Daniel Starke <daniel.starke@siemens.com> | 2022-04-14 02:42:10 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-05-12 12:20:22 +0200 |
| commit | 0114092582cf4695135e3ecc41f134cb196158cb (patch) | |
| tree | c0e8e9cf54ccac99e21349af4fed734e162d8377 /drivers/tty/n_gsm.c | |
| parent | dc53866d5ca95e7028690961c32c7faaea6bb098 (diff) | |
| download | linux-stable-0114092582cf4695135e3ecc41f134cb196158cb.tar.gz linux-stable-0114092582cf4695135e3ecc41f134cb196158cb.tar.bz2 linux-stable-0114092582cf4695135e3ecc41f134cb196158cb.zip | |
tty: n_gsm: fix wrong signal octet encoding in convergence layer type 2
commit 06d5afd4d640eea67f5623e76cd5fc03359b7f3c upstream.
n_gsm is based on the 3GPP 07.010 and its newer version is the 3GPP 27.010.
See https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1516
The changes from 07.010 to 27.010 are non-functional. Therefore, I refer to
the newer 27.010 here. Chapter 5.5.2 describes that the signal octet in
convergence layer type 2 can be either one or two bytes. The length is
encoded in the EA bit. This is set 1 for the last byte in the sequence.
gsmtty_modem_update() handles this correctly but gsm_dlci_data_output()
fails to set EA to 1. There is no case in which we encode two signal octets
as there is no case in which we send out a break signal.
Therefore, always set the EA bit to 1 for the signal octet to fix this.
Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220414094225.4527-5-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/n_gsm.c')
| -rw-r--r-- | drivers/tty/n_gsm.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 4d581140b7a4..4d22d4bd8bfc 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -823,7 +823,7 @@ static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci) break; case 2: /* Unstructed with modem bits. Always one byte as we never send inline break data */ - *dp++ = gsm_encode_modem(dlci); + *dp++ = (gsm_encode_modem(dlci) << 1) | EA; break; } WARN_ON(kfifo_out_locked(dlci->fifo, dp , len, &dlci->lock) != len); |