kernel/linux.git/drivers/tty/serial/serial_core.c, branch v5.15.7

serial: 8250: Fix RTS modem control while in rs485 mode

2021-12-08T08:04:57+00:00

commit f85e04503f369b3f2be28c83fc48b74e19936ebc upstream. Commit f45709df7731 ("serial: 8250: Don't touch RTS modem control while in rs485 mode") sought to prevent user space from interfering with rs485 communication by ignoring a TIOCMSET ioctl() which changes RTS polarity. It did so in serial8250_do_set_mctrl(), which turns out to be too deep in the call stack: When a uart_port is opened, RTS polarity is set by the rs485-aware function uart_port_dtr_rts(). It calls down to serial8250_do_set_mctrl() and that particular RTS polarity change should *not* be ignored. The user-visible result is that on 8250_omap ports which use rs485 with inverse polarity (RTS bit in MCR register is 1 to receive, 0 to send), a newly opened port initially sets up RTS for sending instead of receiving. That's because omap_8250_startup() sets the cached value up->mcr to 0 and omap_8250_restore_regs() subsequently writes it to the MCR register. Due to the commit, serial8250_do_set_mctrl() preserves that incorrect register value: do_sys_openat2 do_filp_open path_openat vfs_open do_dentry_open chrdev_open tty_open uart_open tty_port_open uart_port_activate uart_startup uart_port_startup serial8250_startup omap_8250_startup # up->mcr = 0 uart_change_speed serial8250_set_termios omap_8250_set_termios omap_8250_restore_regs serial8250_out_MCR # up->mcr written tty_port_block_til_ready uart_dtr_rts uart_port_dtr_rts serial8250_set_mctrl omap8250_set_mctrl serial8250_do_set_mctrl # mcr[1] = 1 ignored Fix by intercepting RTS changes from user space in uart_tiocmset() instead. Link: https://lore.kernel.org/linux-serial/20211027111644.1996921-1-baocheng.su@siemens.com/ Fixes: f45709df7731 ("serial: 8250: Don't touch RTS modem control while in rs485 mode") Cc: Chao Zeng Cc: stable@vger.kernel.org # v5.7+ Reported-by: Su Bao Cheng Reported-by: Jan Kiszka Tested-by: Su Bao Cheng Signed-off-by: Lukas Wunner Link: https://lore.kernel.org/r/21170e622a1aaf842a50b32146008b5374b3dd1d.1637596432.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman

serial: core: fix transmit-buffer reset and memleak

2021-12-08T08:04:56+00:00

commit 00de977f9e0aa9760d9a79d1e41ff780f74e3424 upstream. Commit 761ed4a94582 ("tty: serial_core: convert uart_close to use tty_port_close") converted serial core to use tty_port_close() but failed to notice that the transmit buffer still needs to be freed on final close. Not freeing the transmit buffer means that the buffer is no longer cleared on next open so that any ioctl() waiting for the buffer to drain might wait indefinitely (e.g. on termios changes) or that stale data can end up being transmitted in case tx is restarted. Furthermore, the buffer of any port that has been opened would leak on driver unbind. Note that the port lock is held when clearing the buffer pointer due to the ldisc race worked around by commit a5ba1d95e46e ("uart: fix race between uart_put_char() and uart_shutdown()"). Also note that the tty-port shutdown() callback is not called for console ports so it is not strictly necessary to free the buffer page after releasing the lock (cf. d72402145ace ("tty/serial: do not free trasnmit buffer page under port lock")). Link: https://lore.kernel.org/r/319321886d97c456203d5c6a576a5480d07c3478.1635781688.git.baruch@tkos.co.il Fixes: 761ed4a94582 ("tty: serial_core: convert uart_close to use tty_port_close") Cc: stable@vger.kernel.org # 4.9 Cc: Rob Herring Reported-by: Baruch Siach Tested-by: Baruch Siach Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20211108085431.12637-1-johan@kernel.org Signed-off-by: Greg Kroah-Hartman

serial: core: Fix initializing and restoring termios speed

2021-11-18T18:16:03+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: drop put_tty_driver

2021-07-27T10:17:21+00:00

put_tty_driver() is an alias for tty_driver_kref_put(). There is no need for two exported identical functions, therefore switch all users of old put_tty_driver() to new tty_driver_kref_put() and remove the former for good. Cc: Richard Henderson Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Geert Uytterhoeven Cc: Jeff Dike Cc: Richard Weinberger Cc: Anton Ivanov Cc: Chris Zankel Cc: Max Filippov Cc: Arnd Bergmann Cc: Greg Kroah-Hartman 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: Alex Elder Cc: Jiri Slaby Cc: Laurentiu Tudor Cc: Jiri Kosina Cc: David Sterba Cc: Shawn Guo Cc: Sascha Hauer Cc: Pengutronix Kernel Team Cc: Fabio Estevam Cc: NXP Linux Team Cc: Oliver Neukum Cc: Felipe Balbi Cc: Mathias Nyman Cc: Marcel Holtmann Cc: Johan Hedberg Cc: Luiz Augusto von Dentz Acked-by: Alex Elder Acked-by: Christian Borntraeger Acked-by: Max Filippov Acked-by: David Sterba Acked-by: Samuel Iglesias Gonsálvez Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20210723074317.32690-8-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: stop using alloc_tty_driver

2021-07-27T10:17:20+00:00

alloc_tty_driver was deprecated by tty_alloc_driver in commit 7f0bc6a68ed9 (TTY: pass flags to alloc_tty_driver) in 2012. I never got into eliminating alloc_tty_driver until now. So we still have two functions for allocating drivers which might be confusing. So get rid of alloc_tty_driver uses to eliminate it for good in the next patch. Note we need to switch return value checking as tty_alloc_driver uses ERR_PTR. And flags are now a parameter of tty_alloc_driver. Cc: Richard Henderson (odd fixer:ALPHA PORT) Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Geert Uytterhoeven Cc: "James E.J. Bottomley" Cc: Helge Deller Cc: Jeff Dike Cc: Richard Weinberger Cc: Anton Ivanov Cc: Chris Zankel Cc: Max Filippov 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: Laurentiu Tudor Cc: Jiri Kosina Cc: David Sterba Cc: Shawn Guo Cc: Sascha Hauer Cc: Oliver Neukum Cc: Felipe Balbi Cc: Johan Hovold Cc: Marcel Holtmann Cc: Johan Hedberg Cc: Luiz Augusto von Dentz Acked-by: Samuel Iglesias Gonsálvez Acked-by: Max Filippov Acked-by: David Sterba Acked-by: Christian Borntraeger Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20210723074317.32690-5-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

serial: core: Report magic multiplier extra baud rates

2021-07-21T10:35:01+00:00

Report extra baud rates supported above the base rate for ports with the UPF_MAGIC_MULTIPLIER property, so that people have a way to find out that they can be used with their system, e.g.: Serial: 8250/16550 driver, 5 ports, IRQ sharing enabled printk: console [ttyS0] disabled serial8250.0: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A serial8250.0: ttyS0 extra baud rates supported: 230400, 460800 printk: console [ttyS0] enabled printk: bootconsole [uart8250] disabled serial8250.0: ttyS1 at I/O 0x2f8 (irq = 3, base_baud = 115200) is a 16550A serial8250.0: ttyS1 extra baud rates supported: 230400, 460800 serial8250.0: ttyS2 at MMIO 0x1f000900 (irq = 20, base_baud = 230400) is a 16550A Otherwise there is no clear way to figure this out, as the feature is only reported as an obscure TTY flag in bit 16: $ cat /sys/class/tty/ttyS[0-2]/flags 0x10010040 0x10010040 0x90000040 $ Signed-off-by: Maciej W. Rozycki Link: https://lore.kernel.org/r/alpine.DEB.2.21.2106260334170.37803@angie.orcam.me.uk 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