linux-stable.git/drivers/tty/serial/serial_core.c, branch linux-5.14.y

serial: core: Fix initializing and restoring termios speed

2021-11-17T10:03:39+00:00

commit 027b57170bf8bb6999a28e4a5f3d78bf1db0f90c upstream.

Since commit edc6afc54968 ("tty: switch to ktermios and new framework")
termios speed is no longer stored only in c_cflag member but also in new
additional c_ispeed and c_ospeed members. If BOTHER flag is set in c_cflag
then termios speed is stored only in these new members.

Therefore to correctly restore termios speed it is required to store also
ispeed and ospeed members, not only cflag member.

In case only cflag member with BOTHER flag is restored then functions
tty_termios_baud_rate() and tty_termios_input_baud_rate() returns baudrate
stored in c_ospeed / c_ispeed member, which is zero as it was not restored
too. If reported baudrate is invalid (e.g. zero) then serial core functions
report fallback baudrate value 9600. So it means that in this case original
baudrate is lost and kernel changes it to value 9600.

Simple reproducer of this issue is to boot kernel with following command
line argument: "console=ttyXXX,86400" (where ttyXXX is the device name).
For speed 86400 there is no Bnnn constant and therefore kernel has to
represent this speed via BOTHER c_cflag. Which means that speed is stored
only in c_ospeed and c_ispeed members, not in c_cflag anymore.

If bootloader correctly configures serial device to speed 86400 then kernel
prints boot log to early console at speed speed 86400 without any issue.
But after kernel starts initializing real console device ttyXXX then speed
is changed to fallback value 9600 because information about speed was lost.

This patch fixes above issue by storing and restoring also ispeed and
ospeed members, which are required for BOTHER flag.

Fixes: edc6afc54968 ("[PATCH] tty: switch to ktermios and new framework")
Cc: stable@vger.kernel.org
Signed-off-by: Pali Rohár 
Link: https://lore.kernel.org/r/20211002130900.9518-1-pali@kernel.org
Signed-off-by: Greg Kroah-Hartman

tty: make tty_get_{char,frame}_size available

2021-06-15T12:03:26+00:00

Many tty drivers contain code to compute bits count depending on termios
cflags. So extract this code from serial core to two separate tty helper
functions:
* tty_get_char_size -- only size of a character, without flags,
* tty_get_frame_size -- complete size of a frame including flags.

In the next patch, calls to these new functions replace many copies of
this code.

Note that we accept only cflag as a parameter. That's because some
callers like pch_uart_startup or sunsab_console_setup don't have at hand
termios which we could pass around.

Cc: Joe Perches 
Cc: Johan Hovold 
Reviewed-by: Andy Shevchenko 
Signed-off-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20210610090247.2593-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman

Merge 5.13-rc4 into tty-next

2021-05-31T07:44:28+00:00

We need the tty/serial fixes in here as well.

Signed-off-by: Greg Kroah-Hartman

tty/serial: clean up uart_match_port

2021-05-20T14:59:14+00:00

* make parameters const (as they are only read)
* return bool (as comparison results are returned)
* add \n before final return

Signed-off-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20210519072153.3859-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman

serial: drop irq-flags initialisations

2021-05-20T14:24:05+00:00

There's no need to initialise irq-flags variables before saving the
interrupt state.

Drop the redundant initialisations from drivers that got this wrong.

Acked-by: Uwe Kleine-König 
Signed-off-by: Johan Hovold 
Link: https://lore.kernel.org/r/20210519092541.10137-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman

tty: make tty_operations::chars_in_buffer return uint

2021-05-13T16:29:11+00:00

tty_operations::chars_in_buffer is another hook which is expected to
return values >= 0. So make it explicit by the return type too -- use
unsigned int.

Signed-off-by: Jiri Slaby 
Acked-By: Anton Ivanov 
Acked-by: David Sterba 
Cc: Jeff Dike 
Cc: Richard Weinberger 
Cc: Arnd Bergmann 
Cc: Samuel Iglesias Gonsalvez 
Cc: Jens Taprogge 
Cc: Karsten Keil 
Cc: Ulf Hansson 
Cc: "David S. Miller" 
Cc: Jakub Kicinski 
Cc: Heiko Carstens 
Cc: Vasily Gorbik 
Cc: Christian Borntraeger 
Cc: David Lin 
Cc: Johan Hovold 
Cc: Alex Elder 
Cc: Jiri Kosina 
Cc: Shawn Guo 
Cc: Sascha Hauer 
Cc: Oliver Neukum 
Cc: Felipe Balbi 
Cc: Mathias Nyman 
Cc: Marcel Holtmann 
Cc: Johan Hedberg 
Cc: Luiz Augusto von Dentz 
Link: https://lore.kernel.org/r/20210505091928.22010-27-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman

serial: core: fix suspicious security_locked_down() call

2021-05-13T15:08:04+00:00

The commit that added this check did so in a very strange way - first
security_locked_down() is called, its value stored into retval, and if
it's nonzero, then an additional check is made for (change_irq ||
change_port), and if this is true, the function returns. However, if
the goto exit branch is not taken, the code keeps the retval value and
continues executing the function. Then, depending on whether
uport->ops->verify_port is set, the retval value may or may not be reset
to zero and eventually the error value from security_locked_down() may
abort the function a few lines below.

I will go out on a limb and assume that this isn't the intended behavior
and that an error value from security_locked_down() was supposed to
abort the function only in case (change_irq || change_port) is true.

Note that security_locked_down() should be called last in any series of
checks, since the SELinux implementation of this hook will do a check
against the policy and generate an audit record in case of denial. If
the operation was to carry on after calling security_locked_down(), then
the SELinux denial record would be bogus.

See commit 59438b46471a ("security,lockdown,selinux: implement SELinux
lockdown") for how SELinux implements this hook.

Fixes: 794edf30ee6c ("lockdown: Lock down TIOCSSERIAL")
Acked-by: Kees Cook 
Signed-off-by: Ondrej Mosnacek 
Cc: stable 
Link: https://lore.kernel.org/r/20210507115719.140799-1-omosnace@redhat.com
Signed-off-by: Greg Kroah-Hartman

tty: make tty_operations::write_room return uint

2021-05-13T15:03:20+00:00

Line disciplines expect a positive value or zero returned from
tty->ops->write_room (invoked by tty_write_room). So make this
assumption explicit by using unsigned int as a return value. Both of
tty->ops->write_room and tty_write_room.

Signed-off-by: Jiri Slaby 
Acked-by: Laurentiu Tudor 
Acked-by: Alex Elder 
Acked-by: Max Filippov  # xtensa
Acked-by: David Sterba 
Acked-By: Anton Ivanov 
Acked-by: Geert Uytterhoeven 
Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: "James E.J. Bottomley" 
Cc: Helge Deller 
Cc: Jeff Dike 
Cc: Richard Weinberger 
Cc: Chris Zankel 
Cc: Arnd Bergmann 
Cc: Samuel Iglesias Gonsalvez 
Cc: Jens Taprogge 
Cc: Karsten Keil 
Cc: Scott Branden 
Cc: Ulf Hansson 
Cc: "David S. Miller" 
Cc: Jakub Kicinski 
Cc: Heiko Carstens 
Cc: Vasily Gorbik 
Cc: Christian Borntraeger 
Cc: David Lin 
Cc: Johan Hovold 
Cc: Jiri Kosina 
Cc: Shawn Guo 
Cc: Sascha Hauer 
Cc: Oliver Neukum 
Cc: Felipe Balbi 
Cc: Mathias Nyman 
Cc: Marcel Holtmann 
Cc: Johan Hedberg 
Cc: Luiz Augusto von Dentz 
Link: https://lore.kernel.org/r/20210505091928.22010-23-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman

serial: core: return early on unsupported ioctls

2021-04-10T08:36:34+00:00

Drivers can return -ENOIOCTLCMD when an ioctl is not recognised to tell
the upper layers to continue looking for a handler.

This is not the case for the RS485 and ISO7816 ioctls whose handlers
should return -ENOTTY directly in case a serial driver does not
implement the corresponding methods.

Fixes: a5f276f10ff7 ("serial_core: Handle TIOC[GS]RS485 ioctls.")
Fixes: ad8c0eaa0a41 ("tty/serial_core: add ISO7816 infrastructure")
Signed-off-by: Johan Hovold 
Link: https://lore.kernel.org/r/20210407095208.31838-9-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman

serial: core: drop redundant TIOCGSERIAL memset

2021-04-10T08:36:34+00:00

Since commit 5099d234a52a ("serial_core: switch to ->[sg]et_serial()")
the serial structure passed to uart_get_info() has already have been
cleared by the tty layer so drop the redundant memset.

Signed-off-by: Johan Hovold 
Link: https://lore.kernel.org/r/20210407095208.31838-8-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman