linux-stable.git/drivers/tty/tty_ioctl.c, branch linux-6.3.y

tty: Prevent writing chars during tcsetattr TCSADRAIN/FLUSH

2023-05-11T14:16:48+00:00

commit 094fb49a2d0d6827c86d2e0840873e6db0c491d2 upstream.

If userspace races tcsetattr() with a write, the drained condition
might not be guaranteed by the kernel. There is a race window after
checking Tx is empty before tty_set_termios() takes termios_rwsem for
write. During that race window, more characters can be queued by a
racing writer.

Any ongoing transmission might produce garbage during HW's
->set_termios() call. The intent of TCSADRAIN/FLUSH seems to be
preventing such a character corruption. If those flags are set, take
tty's write lock to stop any writer before performing the lower layer
Tx empty check and wait for the pending characters to be sent (if any).

The initial wait for all-writers-done must be placed outside of tty's
write lock to avoid deadlock which makes it impossible to use
tty_wait_until_sent(). The write lock is retried if a racing write is
detected.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Ilpo Järvinen 
Link: https://lore.kernel.org/r/20230317113318.31327-2-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman

tty: Return bool from tty_termios_hw_change()

2023-01-19T15:04:35+00:00

Change tty_termios_hw_change() to return bool.

Reviewed-by: Jiri Slaby 
Reviewed-by: Johan Hovold 
Signed-off-by: Ilpo Järvinen 
Link: https://lore.kernel.org/r/20230117090358.4796-11-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman

termios: start unifying non-UAPI parts of asm/termios.h

2022-09-09T08:44:34+00:00

* new header (linut/termios_internal.h), pulled by the users of those
suckers
* defaults for INIT_C_CC and externs for conversion helpers moved over
there
* remove termios-base.h (empty now)

Signed-off-by: Al Viro 
Link: https://lore.kernel.org/r/YxDmptU7dNGZ+/Hn@ZenIV
Signed-off-by: Greg Kroah-Hartman

termios: uninline conversion helpers

2022-09-09T08:44:34+00:00

default go into drivers/tty/tty_ioctl.c, unusual - into
arch/*/kernel/termios.c (only alpha and sparc have those).

Signed-off-by: Al Viro 
Link: https://lore.kernel.org/r/YxDmeUBHo0s/Ew8b@ZenIV
Signed-off-by: Greg Kroah-Hartman

serial: Make ->set_termios() old ktermios const

2022-08-30T12:22:35+00:00

There should be no reason to adjust old ktermios which is going to get
discarded anyway.

Reviewed-by: Andy Shevchenko 
Signed-off-by: Ilpo Järvinen 
Link: https://lore.kernel.org/r/20220816115739.10928-7-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman

tty: Make tty_termios_copy_hw() old ktermios const

2022-08-30T12:22:34+00:00

There should be no reason to adjust old ktermios which is going to get
discarded anyway.

Reviewed-by: Andy Shevchenko 
Signed-off-by: Ilpo Järvinen 
Link: https://lore.kernel.org/r/20220816115739.10928-5-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman

serial: Support for RS-485 multipoint addresses

2022-06-27T12:44:20+00:00

Add support for RS-485 multipoint addressing using 9th bit [*]. The
addressing mode is configured through ->rs485_config().

ADDRB in termios indicates 9th bit addressing mode is enabled. In this
mode, 9th bit is used to indicate an address (byte) within the
communication line. ADDRB can only be enabled/disabled through
->rs485_config() that is also responsible for setting the destination and
receiver (filter) addresses.

Add traps to detect unwanted changes to struct serial_rs485 layout using
static_assert().

[*] Technically, RS485 is just an electronic spec and does not itself
specify the 9th bit addressing mode but 9th bit seems at least
"semi-standard" way to do addressing with RS485.

Signed-off-by: Ilpo Järvinen 
Link: https://lore.kernel.org/r/20220624204210.11112-6-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman

tty: remove BOTHER ifdefs

2022-05-19T16:26:17+00:00

BOTHER is defined by all architectures since commit d0ffb805b729
("arch/alpha, termios: implement BOTHER, IBSHIFT and termios2").

Reviewed-by: Johan Hovold 
Signed-off-by: Ilpo Järvinen 
Link: https://lore.kernel.org/r/20220513082906.11096-3-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman

tty: remove file from n_tty_ioctl_helper

2021-09-22T14:59:13+00:00

After the previous patch, there are no users of 'file' in
n_tty_ioctl_helper. So remove it also from there.

Cc: Marcel Holtmann 
Cc: Johan Hedberg 
Cc: Luiz Augusto von Dentz 
Cc: Paul Mackerras 
Cc: "David S. Miller" 
Cc: Jakub Kicinski 
Cc: Krzysztof Kozlowski 
Acked-by: Krzysztof Kozlowski 
Signed-off-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20210914091134.17426-6-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman

tty: remove file from tty_mode_ioctl

2021-09-22T14:59:13+00:00

The only user of 'file' parameter in tty_mode_ioctl is a BUG_ON check.
Provided it never crashed for anyone, it's an overkill to pass the
parameter to tty_mode_ioctl only for this check.

If we wanted to check 'file' there, we should handle it in more graceful
way anyway. Not by a BUG == crash.

Cc: Wolfgang Grandegger 
Cc: Marc Kleine-Budde 
Cc: "David S. Miller" 
Cc: Jakub Kicinski 
Cc: Andreas Koensgen 
Cc: Paul Mackerras 
Acked-by: Marc Kleine-Budde 
Signed-off-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20210914091134.17426-5-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman