linux/drivers/tty/serial
Jiri Slaby 4cdd17ba1d TTY: serial_core, add ->install
We need to compute the uart state only on the first open. This is
usually what is done in the ->install hook. serial_core used to do this
in ->open on every open. So move it to ->install.

As a side effect, it ensures the state is set properly in the window
after tty_init_dev is called, but before uart_open. This fixes a bunch
of races between tty_open and flush_to_ldisc we were dealing with
recently.

One of such bugs was attempted to fix in commit fedb576064 (serial:
fix race between flush_to_ldisc and tty_open), but it only took care of
a couple of functions (uart_start and uart_unthrottle).  I was able to
reproduce the crash on a SLE system, but in uart_write_room which is
also called from flush_to_ldisc via process_echoes. I was *unable* to
reproduce the bug locally. It is due to having this patch in my queue
since 2012!

 general protection fault: 0000 [#1] SMP KASAN PTI
 CPU: 1 PID: 5 Comm: kworker/u4:0 Tainted: G             L 4.12.14-396-default #1 SLE15-SP1 (unreleased)
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c89-prebuilt.qemu.org 04/01/2014
 Workqueue: events_unbound flush_to_ldisc
 task: ffff8800427d8040 task.stack: ffff8800427f0000
 RIP: 0010:uart_write_room+0xc4/0x590
 RSP: 0018:ffff8800427f7088 EFLAGS: 00010202
 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
 RDX: 000000000000002f RSI: 00000000000000ee RDI: ffff88003888bd90
 RBP: ffffffffb9545850 R08: 0000000000000001 R09: 0000000000000400
 R10: ffff8800427d825c R11: 000000000000006e R12: 1ffff100084fee12
 R13: ffffc900004c5000 R14: ffff88003888bb28 R15: 0000000000000178
 FS:  0000000000000000(0000) GS:ffff880043300000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000561da0794148 CR3: 000000000ebf4000 CR4: 00000000000006e0
 Call Trace:
  tty_write_room+0x6d/0xc0
  __process_echoes+0x55/0x870
  n_tty_receive_buf_common+0x105e/0x26d0
  tty_ldisc_receive_buf+0xb7/0x1c0
  tty_port_default_receive_buf+0x107/0x180
  flush_to_ldisc+0x35d/0x5c0
...

0 in rbx means tty->driver_data is NULL in uart_write_room. 0x178 is
tried to be dereferenced (0x178 >> 3 is 0x2f in rdx) at
uart_write_room+0xc4. 0x178 is exactly (struct uart_state *)NULL->refcount
used in uart_port_lock from uart_write_room.

So revert the upstream commit here as my local patch should fix the
whole family.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Wang Li <wangli39@baidu.com>
Cc: Zhang Yu <zhangyu31@baidu.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-25 11:37:41 +02:00
..
8250 tty: fix up a few remaining files without SPDX identifiers 2019-04-04 18:48:43 +02:00
cpm_uart tty: add SPDX identifiers to Kconfig and Makefiles 2019-04-04 18:48:43 +02:00
jsm tty: add SPDX identifiers to Kconfig and Makefiles 2019-04-04 18:48:43 +02:00
21285.c
altera_jtaguart.c
altera_uart.c
amba-pl010.c
amba-pl011.c serial: set suppress_bind_attrs flag only if builtin 2018-11-09 09:07:17 -08:00
amba-pl011.h
apbuart.c
apbuart.h
ar933x_uart.c serial: ar933x_uart: Fix build failure with disabled console 2019-03-19 15:37:44 +01:00
arc_uart.c
atmel_serial.c tty/serial: atmel: RS485 HD w/DMA: enable RX after TX is stopped 2019-03-28 00:27:48 +09:00
atmel_serial.h tty/serial: atmel: add ISO7816 support 2018-10-02 13:38:55 -07:00
bcm63xx_uart.c
clps711x.c serial: clps711x: Remove board support 2019-01-08 16:55:18 +01:00
digicolor-usart.c
dz.c
dz.h
earlycon-arm-semihost.c
earlycon-riscv-sbi.c tty/serial: use uart_console_write in the RISC-V SBL early console 2019-01-23 15:41:50 -08:00
earlycon.c
efm32-uart.c
fsl_lpuart.c serial: fsl_lpuart: DMA support for 32-bit variant 2019-01-30 09:31:30 +01:00
icom.c
icom.h
ifx6x60.c
ifx6x60.h
imx.c serial: imx: fix error handling in console_setup 2018-11-27 09:56:20 +01:00
ioc3_serial.c
ioc4_serial.c
ip22zilog.c
ip22zilog.h
Kconfig serial: Add Milbeaut serial control 2019-04-16 15:21:34 +02:00
kgdb_nmi.c
kgdboc.c Disable kgdboc failed by echo space to /sys/module/kgdboc/parameters/kgdboc 2019-03-28 00:27:48 +09:00
lantiq.c serial: lantiq: Do not swap register read/writes 2019-01-08 16:53:36 +01:00
lpc32xx_hs.c tty: serial: lpc32xx_hs: fix missing console boot messages 2019-01-18 11:23:00 +01:00
Makefile serial: Add Milbeaut serial control 2019-04-16 15:21:34 +02:00
max310x.c serial: max310x: Fix to avoid potential NULL pointer dereference 2019-03-19 15:37:43 +01:00
max3100.c
mcf.c
men_z135_uart.c
meson_uart.c tty: serial: meson: if no alias specified use an available id 2019-01-18 11:22:22 +01:00
milbeaut_usio.c serial: Fix using plain integer instead of Null pointer 2019-04-25 11:37:41 +02:00
mpc52xx_uart.c
mps2-uart.c serial: mps2-uart: Add parentheses around conditional in mps2_uart_shutdown 2019-01-31 19:34:10 +01:00
mpsc.c
msm_serial.c tty: serial: msm_serial: Remove __init from msm_console_setup() 2019-02-19 13:42:08 +01:00
mux.c
mvebu-uart.c serial: mvebu-uart: Fix to avoid a potential NULL pointer dereference 2019-03-19 15:37:43 +01:00
mxs-auart.c tty: mxs-auart: fix a potential NULL pointer dereference 2019-03-19 15:37:43 +01:00
netx-serial.c
omap-serial.c
owl-uart.c
pch_uart.c PCI: Move Rohm Vendor ID to generic list 2019-02-01 17:24:52 -06:00
pic32_uart.c serial: set suppress_bind_attrs flag only if builtin 2018-11-09 09:07:17 -08:00
pic32_uart.h
pmac_zilog.c tty: Use of_node_name_{eq,prefix} for node name comparisons 2018-12-17 16:12:17 +01:00
pmac_zilog.h
pnx8xxx_uart.c
pxa.c
qcom_geni_serial.c tty: serial: qcom_geni_serial: Initialize baud in qcom_geni_console_setup 2019-03-19 15:37:44 +01:00
rda-uart.c tty: serial: Add RDA8810PL UART driver 2018-12-31 13:10:01 -08:00
rp2.c
sa1100.c
samsung.c tty: serial: samsung: Enable baud clock during initialisation 2019-02-19 13:42:08 +01:00
samsung.h
sb1250-duart.c
sc16is7xx.c Merge 5.1-rc6 into tty-next 2019-04-21 23:20:08 +02:00
sccnxp.c serial: sccnxp: Allow to use non-standard baud rates 2018-12-20 16:26:59 +01:00
serial_core.c TTY: serial_core, add ->install 2019-04-25 11:37:41 +02:00
serial_ks8695.c
serial_mctrl_gpio.c
serial_mctrl_gpio.h
serial_txx9.c
serial-tegra.c serial: tegra: fix some spelling mistakes 2018-11-09 08:58:18 -08:00
sh-sci.c serial: sh-sci: Fix HSCIF RX sampling point adjustment 2019-04-16 15:24:38 +02:00
sh-sci.h
sirfsoc_uart.c
sirfsoc_uart.h
sn_console.c tty: fix up a few remaining files without SPDX identifiers 2019-04-04 18:48:43 +02:00
sprd_serial.c serial: sprd: Fix a copy-paste err in sprd_request_dma() 2019-04-16 15:21:33 +02:00
st-asc.c
stm32-usart.c
stm32-usart.h
suncore.c tty: Use of_node_name_{eq,prefix} for node name comparisons 2018-12-17 16:12:17 +01:00
sunhv.c
sunsab.c
sunsab.h
sunsu.c TTY/Serial driver patches for 4.21-rc1 2018-12-28 20:33:54 -08:00
sunzilog.c
sunzilog.h
tegra-tcu.c serial: Add Tegra Combined UART driver 2019-01-30 09:31:31 +01:00
timbuart.c
timbuart.h
uartlite.c serial-uartlite: fix null pointer dereference on pointer port 2018-11-27 09:08:15 +01:00
ucc_uart.c
vr41xx_siu.c
vt8500_serial.c
xilinx_uartps.c tty: xilinx_uartps: Correct return value in probe 2019-03-01 18:07:34 +01:00
zs.c
zs.h