linux-stable.git/drivers/tty, branch v4.16.7

earlycon: Use a pointer table to fix __earlycon_table stride

2018-05-01T19:47:28+00:00

commit dd709e72cb934eefd44de8d9969097173fbf45dc upstream.

Commit 99492c39f39f ("earlycon: Fix __earlycon_table stride") tried to fix
__earlycon_table stride by forcing the earlycon_id struct alignment to 32
and asking the linker to 32-byte align the __earlycon_table symbol.  This
fix was based on commit 07fca0e57fca92 ("tracing: Properly align linker
defined symbols") which tried a similar fix for the tracing subsystem.

However, this fix doesn't quite work because there is no guarantee that
gcc will place structures packed into an array format.  In fact, gcc 4.9
chooses to 64-byte align these structs by inserting additional padding
between the entries because it has no clue that they are supposed to be in
an array.  If we are unlucky, the linker will assign symbol
"__earlycon_table" to a 32-byte aligned address which does not correspond
to the 64-byte aligned contents of section "__earlycon_table".

To address this same problem, the fix to the tracing system was
subsequently re-implemented using a more robust table of pointers approach
by commits:
 3d56e331b653 ("tracing: Replace syscall_meta_data struct array with pointer array")
 654986462939 ("tracepoints: Fix section alignment using pointer array")
 e4a9ea5ee7c8 ("tracing: Replace trace_event struct array with pointer array")

Let's use this same "array of pointers to structs" approach for
EARLYCON_TABLE.

Fixes: 99492c39f39f ("earlycon: Fix __earlycon_table stride")
Signed-off-by: Daniel Kurtz 
Suggested-by: Aaron Durbin 
Reviewed-by: Rob Herring 
Tested-by: Guenter Roeck 
Reviewed-by: Guenter Roeck 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

tty: Use __GFP_NOFAIL for tty_ldisc_get()

2018-05-01T19:47:21+00:00

commit bcdd0ca8cb8730573afebcaae4138f8f4c8eaa20 upstream.

syzbot is reporting crashes triggered by memory allocation fault injection
at tty_ldisc_get() [1]. As an attempt to handle OOM in a graceful way, we
have tried commit 5362544bebe85071 ("tty: don't panic on OOM in
tty_set_ldisc()"). But we reverted that attempt by commit a8983d01f9b7d600
("Revert "tty: don't panic on OOM in tty_set_ldisc()"") due to reproducible
crash. We should spend resource for finding and fixing race condition bugs
rather than complicate error paths for 2 * sizeof(void *) bytes allocation
failure.

[1] https://syzkaller.appspot.com/bug?id=489d33fa386453859ead58ff5171d43772b13aa3

Signed-off-by: Tetsuo Handa 
Reported-by: syzbot 
Cc: Michal Hocko 
Cc: Vegard Nossum 
Cc: Dmitry Vyukov 
Cc: Jiri Slaby 
Cc: Peter Hurley 
Cc: One Thousand Gnomes 
Cc: Linus Torvalds 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman

tty: Avoid possible error pointer dereference at tty_ldisc_restore().

2018-05-01T19:47:21+00:00

commit 598c2d41ff44889dd8eced4f117403e472158d85 upstream.

syzbot is reporting crashes [1] triggered by memory allocation failure at
tty_ldisc_get() from tty_ldisc_restore(). While syzbot stops at WARN_ON()
due to panic_on_warn == true, panic_on_warn == false will after all trigger
an OOPS by dereferencing old->ops->num if IS_ERR(old) == true.

We can simplify tty_ldisc_restore() as three calls (old->ops->num, N_TTY,
N_NULL) to tty_ldisc_failto() in addition to avoiding possible error
pointer dereference.

If someone reports kernel panic triggered by forcing all memory allocations
for tty_ldisc_restore() to fail, we can consider adding __GFP_NOFAIL for
tty_ldisc_restore() case.

[1] https://syzkaller.appspot.com/bug?id=6ac359c61e71d22e06db7f8f88243feb11d927e7

Reported-by: syzbot+40b7287c2dc987c48c81@syzkaller.appspotmail.com
Signed-off-by: Tetsuo Handa 
Cc: Greg Kroah-Hartman 
Cc: Jiri Slaby 
Cc: Dmitry Vyukov 
Cc: Johannes Weiner 
Cc: Alan Cox 
Cc: Christoph Hellwig 
Cc: Michal Hocko 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

tty: n_gsm: Fix DLCI handling for ADM mode if debug & 2 is not set

2018-05-01T19:47:21+00:00

commit b2d89ad9c9682e795ed6eeb9ed455789ad6cedf1 upstream.

At least on droid 4 with control channel in ADM mode, there is no response
to Modem Status Command (MSC). Currently gsmtty_modem_update() expects to
have data in dlci->modem_rx unless debug & 2 is set. This means that on
droid 4, things only work if debug & 2 is set.

Let's fix the issue by ignoring empty dlci->modem_rx for ADM mode. In
the AMD mode, CMD_MSC will never respond and gsm_process_modem() won't
get called to set dlci->modem_rx.

And according to ts_127010v140000p.pdf, MSC is only relevant if basic
option is chosen, so let's test for that too.

Fixes: ea3d8465ab9b ("tty: n_gsm: Allow ADM response in addition to UA for control dlci")
Cc: linux-serial@vger.kernel.org
Cc: Alan Cox 
Cc: Dan Williams 
Cc: Jiri Prchal 
Cc: Jiri Slaby 
Cc: Marcel Partap 
Cc: Merlijn Wajer 
Cc: Michael Nazzareno Trimarchi 
Cc: Michael Scott 
Cc: Pavel Machek 
Cc: Peter Hurley 
Cc: Russ Gorby 
Cc: Sascha Hauer 
Cc: Sebastian Reichel 
Signed-off-by: Tony Lindgren 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

tty: n_gsm: Fix long delays with control frame timeouts in ADM mode

2018-05-01T19:47:21+00:00

commit e9ec22547986dd32c5c70da78107ce35dbff1344 upstream.

Commit ea3d8465ab9b ("tty: n_gsm: Allow ADM response in addition to UA for
control dlci") added support for DLCI to stay in Asynchronous Disconnected
Mode (ADM). But we still get long delays waiting for commands to other
DLCI to complete:

--> 5) C: SABM(P)
Q>  0) C: UIH(F)
Q>  0) C: UIH(F)
Q>  0) C: UIH(F)
...

This happens because gsm_control_send() sets cretries timer to T2 that is
by default set to 34. This will cause resend for T2 times for the control
frame. In ADM mode, we will never get a response so the control frame, so
retries are just delaying all the commands.

Let's fix the issue by setting DLCI_MODE_ADM flag after detecting the ADM
mode for the control DLCI. Then we can use that in gsm_control_send() to
set retries to 1. This means the control frame will be sent once allowing
the other end at an opportunity to switch from ADM to ABM mode.

Note that retries will be decremented in gsm_control_retransmit() so
we don't want to set it to 0 here.

Fixes: ea3d8465ab9b ("tty: n_gsm: Allow ADM response in addition to UA for control dlci")
Cc: linux-serial@vger.kernel.org
Cc: Alan Cox 
Cc: Dan Williams 
Cc: Jiri Prchal 
Cc: Jiri Slaby 
Cc: Marcel Partap 
Cc: Merlijn Wajer 
Cc: Michael Nazzareno Trimarchi 
Cc: Michael Scott 
Cc: Pavel Machek 
Cc: Peter Hurley 
Cc: Russ Gorby 
Cc: Sascha Hauer 
Cc: Sebastian Reichel 
Signed-off-by: Tony Lindgren 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

tty: Don't call panic() at tty_ldisc_init()

2018-05-01T19:47:21+00:00

commit 903f9db10f18f735e62ba447147b6c434b6af003 upstream.

syzbot is reporting kernel panic [1] triggered by memory allocation failure
at tty_ldisc_get() from tty_ldisc_init(). But since both tty_ldisc_get()
and caller of tty_ldisc_init() can cleanly handle errors, tty_ldisc_init()
does not need to call panic() when tty_ldisc_get() failed.

[1] https://syzkaller.appspot.com/bug?id=883431818e036ae6a9981156a64b821110f39187

Signed-off-by: Tetsuo Handa 
Reported-by: syzbot 
Cc: Greg Kroah-Hartman 
Cc: Jiri Slaby 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

serial: mvebu-uart: Fix local flags handling on termios update

2018-05-01T19:47:20+00:00

commit 46c6975a1fd9794ed979565235d24b2f5004e014 upstream.

Commit 68a0db1d7da2 reworked the baud rate selection, but also added
a (not so) subtle change in the way the local flags (c_lflag in the
termios structure) are handled, forcing the new flags to always be the
same as the old ones.

The reason for that particular change is both obscure and undocumented.
It also completely breaks userspace. Something as trivial as getty is
unusable:


	Debian GNU/Linux 9 sy-borg ttyMV0

	sy-borg login: root
	root
	[timeout]

	Debian GNU/Linux 9 sy-borg ttyMV0


which is quite obvious in retrospect: getty cannot get in control of
the echo mode, is stuck in canonical mode, and times out without ever
seeing anything valid. It also begs the question of how this change was
ever tested.

The fix is pretty obvious: stop messing with c_lflag, and the world
will be a happier place.

Cc: stable@vger.kernel.org # 4.15+
Fixes: 68a0db1d7da2 ("serial: mvebu-uart: add function to change baudrate")
Signed-off-by: Marc Zyngier 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman

vt: change SGR 21 to follow the standards

2018-04-08T12:29:52+00:00

commit 65d9982d7e523a1a8e7c9af012da0d166f72fc56 upstream.

ECMA-48 [1] (aka ISO 6429) has defined SGR 21 as "doubly underlined"
since at least March 1984.  The Linux kernel has treated it as SGR 22
"normal intensity" since it was added in Linux-0.96b in June 1992.
Before that, it was simply ignored.  Other terminal emulators have
either ignored it, or treat it as double underline now.  xterm for
example added support in its 304 release (May 2014) [2] where it was
previously ignoring it.

Changing this behavior shouldn't be an issue:
- It isn't a named capability in ncurses's terminfo database, so no
  script is using libtinfo/libcurses to look this up, or using tput
  to query & output the right sequence.
- Any script assuming SGR 21 will reset intensity in all terminals
  already do not work correctly on non-Linux VTs (including running
  under screen/tmux/etc...).
- If someone has written a script that only runs in the Linux VT, and
  they're using SGR 21 (instead of SGR 22), the output should still
  be readable.

imo it's important to change this as the Linux VT's non-conformance
is sometimes used as an argument for other terminal emulators to not
implement SGR 21 at all, or do so incorrectly.

[1]: https://www.ecma-international.org/publications/standards/Ecma-048.htm
[2]: https://github.com/ThomasDickey/xterm-snapshots/commit/2fd29cb98d214cb536bcafbee00bc73b3f1eeb9d

Signed-off-by: Mike Frysinger 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

serial: 8250: Add Nuvoton NPCM UART

2018-04-08T12:29:49+00:00

commit f597fbce38d230af95384f4a04e0a13a1d0ad45d upstream.

The Nuvoton UART is almost compatible with the 8250 driver when probed
via the 8250_of driver, however it requires some extra configuration
at startup.

Reviewed-by: Rob Herring 
Signed-off-by: Joel Stanley 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

tty: vt: fix up tabstops properly

2018-03-25T17:04:00+00:00

Tabs on a console with long lines do not wrap properly, so correctly
account for the line length when computing the tab placement location.

Reported-by: James Holderness 
Signed-off-by: Greg Kroah-Hartman 
Cc: stable 
Signed-off-by: Linus Torvalds