linux-stable.git/drivers/tty, branch v3.16.65

tty/ldsem: Wake up readers after timed out down_write()

2019-04-04T15:13:46+00:00

commit 231f8fd0cca078bd4396dd7e380db813ac5736e2 upstream.

ldsem_down_read() will sleep if there is pending writer in the queue.
If the writer times out, readers in the queue should be woken up,
otherwise they may miss a chance to acquire the semaphore until the last
active reader will do ldsem_up_read().

There was a couple of reports where there was one active reader and
other readers soft locked up:
  Showing all locks held in the system:
  2 locks held by khungtaskd/17:
   #0:  (rcu_read_lock){......}, at: watchdog+0x124/0x6d1
   #1:  (tasklist_lock){.+.+..}, at: debug_show_all_locks+0x72/0x2d3
  2 locks held by askfirst/123:
   #0:  (&tty->ldisc_sem){.+.+.+}, at: ldsem_down_read+0x46/0x58
   #1:  (&ldata->atomic_read_lock){+.+...}, at: n_tty_read+0x115/0xbe4

Prevent readers wait for active readers to release ldisc semaphore.

Link: lkml.kernel.org/r/20171121132855.ajdv4k6swzhvktl6@wfg-t540p.sh.intel.com
Link: lkml.kernel.org/r/20180907045041.GF1110@shao2-debian
Cc: Jiri Slaby 
Cc: Peter Zijlstra 
Reported-by: kernel test robot 
Signed-off-by: Dmitry Safonov 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Ben Hutchings

serial: imx: fix error handling in console_setup

2019-04-04T15:13:45+00:00

commit 63fd4b94b948c14eeb27a3bbf50ea0f7f0593bad upstream.

The ipg clock only needs to be unprepared in case preparing
per clock fails. The ipg clock has already disabled at the point.

Fixes: 1cf93e0d5488 ("serial: imx: remove the uart_console() check")
Signed-off-by: Stefan Agner 
Reviewed-by: Uwe Kleine-König 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Ben Hutchings

kgdboc: fix KASAN global-out-of-bounds bug in param_set_kgdboc_var()

2019-02-11T17:54:22+00:00

commit dada6a43b0402eba438a17ac86fdc64ac56a4607 upstream.

This patch is trying to fix KE issue due to
"BUG: KASAN: global-out-of-bounds in param_set_kgdboc_var+0x194/0x198"
reported by Syzkaller scan."

[26364:syz-executor0][name:report8t]BUG: KASAN: global-out-of-bounds in param_set_kgdboc_var+0x194/0x198
[26364:syz-executor0][name:report&]Read of size 1 at addr ffffff900e44f95f by task syz-executor0/26364
[26364:syz-executor0][name:report&]
[26364:syz-executor0]CPU: 7 PID: 26364 Comm: syz-executor0 Tainted: G W 0
[26364:syz-executor0]Call trace:
[26364:syz-executor0][] dump_bacIctrace+Ox0/0x470
[26364:syz-executor0][] show_stack+0x20/0x30
[26364:syz-executor0][] dump_stack+Oxd8/0x128
[26364:syz-executor0][] print_address_description +0x80/0x4a8
[26364:syz-executor0][] kasan_report+Ox178/0x390
[26364:syz-executor0][] _asan_report_loadi_noabort+Ox18/0x20
[26364:syz-executor0][] param_set_kgdboc_var+Ox194/0x198
[26364:syz-executor0][] param_attr_store+Ox14c/0x270
[26364:syz-executor0][] module_attr_store+0x60/0x90
[26364:syz-executor0][] sysfs_kl_write+Ox100/0x158
[26364:syz-executor0][] kernfs_fop_write+0x27c/0x3a8
[26364:syz-executor0][] do_loop_readv_writev+0x114/0x1b0
[26364:syz-executor0][] do_readv_writev+0x4f8/0x5e0
[26364:syz-executor0][] vfs_writev+0x7c/Oxb8
[26364:syz-executor0][] SyS_writev+Oxcc/0x208
[26364:syz-executor0][] elO_svc_naked +0x24/0x28
[26364:syz-executor0][name:report&]
[26364:syz-executor0][name:report&]The buggy address belongs to the variable:
[26364:syz-executor0][name:report&] kgdb_tty_line+Ox3f/0x40
[26364:syz-executor0][name:report&]
[26364:syz-executor0][name:report&]Memory state around the buggy address:
[26364:syz-executor0] ffffff900e44f800: 00 00 00 00 00 04 fa fa fa fa fa fa 00 fa fa fa
[26364:syz-executor0] ffffff900e44f880: fa fa fa fa 00 fa fa fa fa fa fa fa 00 fa fa fa
[26364:syz-executor0]> ffffff900e44f900: fa fa fa fa 04 fa fa fa fa fa fa fa 00 00 00 00
[26364:syz-executor0][name:report&]                                       ^
[26364:syz-executor0] ffffff900e44f980: 00 fa fa fa fa fa fa fa 04 fa fa fa fa fa fa fa
[26364:syz-executor0] ffffff900e44fa00: 04 fa fa fa fa fa fa fa 00 fa fa fa fa fa fa fa
[26364:syz-executor0][name:report&]
[26364:syz-executor0][name:panic&]Disabling lock debugging due to kernel taint
[26364:syz-executor0]------------[cut here]------------

After checking the source code, we've found there might be an out-of-bounds
access to "config[len - 1]" array when the variable "len" is zero.

Signed-off-by: Macpaul Lin 
Acked-by: Daniel Thompson 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Ben Hutchings

termios, tty/tty_baudrate.c: fix buffer overrun

2019-02-11T17:53:54+00:00

commit 991a25194097006ec1e0d2e0814ff920e59e3465 upstream.

On architectures with CBAUDEX == 0 (Alpha and PowerPC), the code in tty_baudrate.c does
not do any limit checking on the tty_baudrate[] array, and in fact a
buffer overrun is possible on both architectures. Add a limit check to
prevent that situation.

This will be followed by a much bigger cleanup/simplification patch.

Signed-off-by: H. Peter Anvin (Intel) 
Requested-by: Cc: Johan Hovold 
Cc: Jiri Slaby 
Cc: Al Viro 
Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: Thomas Gleixner 
Cc: Kate Stewart 
Cc: Philippe Ombredanne 
Cc: Eugene Syromiatnikov 
Cc: Alan Cox 
Signed-off-by: Greg Kroah-Hartman 
[bwh: Backported to 3.16: adjust filename, context]
Signed-off-by: Ben Hutchings

kgdboc: Passing ekgdboc to command line causes panic

2019-02-11T17:53:21+00:00

commit 1bd54d851f50dea6af30c3e6ff4f3e9aab5558f9 upstream.

kgdboc_option_setup does not check input argument before passing it
to strlen. The argument would be a NULL pointer if "ekgdboc", without
its value, is set in command line and thus cause the following panic.

PANIC: early exception 0xe3 IP 10:ffffffff8fbbb620 error 0 cr2 0x0
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.18-rc8+ #1
[    0.000000] RIP: 0010:strlen+0x0/0x20
...
[    0.000000] Call Trace
[    0.000000]  ? kgdboc_option_setup+0x9/0xa0
[    0.000000]  ? kgdboc_early_init+0x6/0x1b
[    0.000000]  ? do_early_param+0x4d/0x82
[    0.000000]  ? parse_args+0x212/0x330
[    0.000000]  ? rdinit_setup+0x26/0x26
[    0.000000]  ? parse_early_options+0x20/0x23
[    0.000000]  ? rdinit_setup+0x26/0x26
[    0.000000]  ? parse_early_param+0x2d/0x39
[    0.000000]  ? setup_arch+0x2f7/0xbf4
[    0.000000]  ? start_kernel+0x5e/0x4c2
[    0.000000]  ? load_ucode_bsp+0x113/0x12f
[    0.000000]  ? secondary_startup_64+0xa5/0xb0

This patch adds a check to prevent the panic.

Cc: jason.wessel@windriver.com
Cc: gregkh@linuxfoundation.org
Cc: jslaby@suse.com
Signed-off-by: He Zhe 
Reviewed-by: Daniel Thompson 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Ben Hutchings

tty: vt_ioctl: fix potential Spectre v1

2018-12-16T22:09:20+00:00

commit e97267cb4d1ee01ca0929638ec0fcbb0904f903d upstream.

vsa.console is indirectly controlled by user-space, hence leading to
a potential exploitation of the Spectre variant 1 vulnerability.

This issue was detected with the help of Smatch:

drivers/tty/vt/vt_ioctl.c:711 vt_ioctl() warn: potential spectre issue
'vc_cons' [r]

Fix this by sanitizing vsa.console before using it to index vc_cons

Notice that given that speculation windows are large, the policy is
to kill the speculation on the first load and not worry if it can be
completed with a dependent load/store [1].

[1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2

Signed-off-by: Gustavo A. R. Silva 
Reviewed-by: Alan Cox 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Ben Hutchings

serial: cpm_uart: return immediately from console poll

2018-12-16T22:09:20+00:00

commit be28c1e3ca29887e207f0cbcd294cefe5074bab6 upstream.

kgdb expects poll function to return immediately and
returning NO_POLL_CHAR when no character is available.

Fixes: f5316b4aea024 ("kgdb,8250,pl011: Return immediately from console poll")
Cc: Jason Wessel 
Signed-off-by: Christophe Leroy 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Ben Hutchings

tty: fix termios input-speed encoding when using BOTHER

2018-12-16T22:08:15+00:00

commit 1cee38f0363a88db374e50b232ca17b9a4c12fa0 upstream.

When the termios CIBAUD bits are left unset (i.e. B0), we use the same
output and input speed and should leave CIBAUD unchanged.

When the user requests a rate using BOTHER and c_ospeed which the driver
cannot set exactly, the driver can report back the actual baud rate
using tty_termios_encode_baud_rate(). If this rate is close enough to a
standard rate however, we could end up setting CIBAUD to a Bfoo value
despite the user having left it unset.

This in turn could lead to an unexpected input rate being set on
subsequent termios updates.

Fix this by using a zero tolerance value also for the input rate when
CIBAUD is clear so that the matching logic works as expected.

Fixes: 78137e3b34e1 ("[PATCH] tty: improve encode_baud_rate logic")
Signed-off-by: Johan Hovold 
Signed-off-by: Greg Kroah-Hartman 
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings

tty: fix termios input-speed encoding

2018-12-16T22:08:15+00:00

commit fada18c48d774b9e837928ecdce6a5d5fdd11ee7 upstream.

Make sure to clear the CIBAUD bits before OR-ing the new mask when
encoding the termios input baud rate.

This could otherwise lead to an incorrect input rate being reported back
and incidentally set on subsequent termios updates.

Fixes: edc6afc54968 ("[PATCH] tty: switch to ktermios and new framework")
Signed-off-by: Johan Hovold 
Signed-off-by: Greg Kroah-Hartman 
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings

tty: fix typo in comment of tty_termios_encode_baud_rate

2018-12-16T22:08:15+00:00

commit a1d51aa2214cea3f91611893610a2f769cada0e7 upstream.

Signed-off-by: Matthias Brugger 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Ben Hutchings