tty: n_gsm: fix race condition in gsmld_write()

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[ Upstream commit 32dd59f969 ]

The function may be used by the user directly and also by the n_gsm
internal functions. They can lead into a race condition which results in
interleaved frames if both are writing at the same time. The receiving side
is not able to decode those interleaved frames correctly.

Add a lock around the low side tty write to avoid race conditions and frame
interleaving between user originated writes and n_gsm writes.

Fixes: e1eaea46bb ("tty: n_gsm line discipline")
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20220701061652.39604-9-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Daniel Starke 2022-07-01 08:16:52 +02:00 • committed by Greg Kroah-Hartman

parent 51556905dd

commit 5320aa45f5

1 changed files with 17 additions and 4 deletions

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drivers/tty/n_gsm.c

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