Bluetooth: rfcomm: fix modem control handling

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commit 91d35ec9b3 upstream.

The RFCOMM driver confuses the local and remote modem control signals,
which specifically means that the reported DTR and RTS state will
instead reflect the remote end (i.e. DSR and CTS).

This issue dates back to the original driver (and a follow-on update)
merged in 2002, which resulted in a non-standard implementation of
TIOCMSET that allowed controlling also the TS07.10 IC and DV signals by
mapping them to the RI and DCD input flags, while TIOCMGET failed to
return the actual state of DTR and RTS.

Note that the bogus control of input signals in tiocmset() is just
dead code as those flags will have been masked out by the tty layer
since 2003.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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Johan Hovold 2025-10-23 14:05:30 +02:00 • committed by Greg Kroah-Hartman

parent efaf89a75a

commit e159cd26fa

1 changed files with 11 additions and 15 deletions

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net/bluetooth/rfcomm/tty.c

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