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Jiri Slaby ec8a9eb2a6 TTY: serial_core, add ->install 
commit 4cdd17ba1d upstream.

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>
2019-06-11 12:20:56 +02:00
..
hvc tty: Don't force RISCV SBI console as preferred console 2019-05-22 07:37:43 +02:00
ipwireless tty: ipwireless: fix missing checks for ioremap 2019-05-31 06:46:30 -07:00
serdev serdev: add dev_pm_domain_attach|detach() 2018-07-15 12:23:53 +02:00
serial TTY: serial_core, add ->install 2019-06-11 12:20:56 +02:00
vt vt/fbcon: deinitialize resources in visual_init() after failed memory allocation 2019-06-09 09:17:21 +02:00
amiserial.c
cyclades.c
ehv_bytechan.c
goldfish.c
isicom.c
Kconfig tty: ldisc: add sysctl to prevent autoloading of ldiscs 2019-04-17 08:38:47 +02:00
Makefile
mips_ejtag_fdc.c
moxa.c
moxa.h
mxser.c
mxser.h
n_gsm.c
n_hdlc.c tty/n_hdlc: fix __might_sleep warning 2019-01-31 08:14:36 +01:00
n_null.c
n_r3964.c
n_tracerouter.c
n_tracesink.c
n_tracesink.h
n_tty.c tty: wipe buffer if not echoing data 2018-12-01 09:37:34 +01:00
nozomi.c
pty.c pty: fix O_CLOEXEC for TIOCGPTPEER 2018-07-21 09:08:47 +02:00
rocket.c tty: rocket: Fix possible buffer overwrite on register_PCI 2018-08-02 10:11:32 +02:00
rocket.h
rocket_int.h
synclink.c
synclink_gt.c
synclinkmp.c
sysrq.c signal: Pass pid type into do_send_sig_info 2018-07-21 12:57:35 -05:00
tty_audit.c
tty_baudrate.c termios, tty/tty_baudrate.c: fix buffer overrun 2018-11-21 09:19:20 +01:00
tty_buffer.c tty: increase the default flip buffer limit to 2*640K 2019-04-05 22:33:13 +02:00
tty_io.c tty: ldisc: add sysctl to prevent autoloading of ldiscs 2019-04-17 08:38:47 +02:00
tty_ioctl.c
tty_jobctrl.c
tty_ldisc.c tty: ldisc: add sysctl to prevent autoloading of ldiscs 2019-04-17 08:38:47 +02:00
tty_ldsem.c tty/ldsem: Wake up readers after timed out down_write() 2019-01-22 21:40:28 +01:00
tty_mutex.c
tty_port.c tty: do not set TTY_IO_ERROR flag if console port 2018-12-13 09:16:22 +01:00
vcc.c