tty: add the option to have a tty reject a new ldisc

... and use it to limit the virtual terminals to just N_TTY. They are
kind of special, and in particular, the "con_write()" routine violates
the

tty: add the option to have a tty reject a new ldisc

... and use it to limit the virtual terminals to just N_TTY. They are
kind of special, and in particular, the "con_write()" routine violates
the "writes cannot sleep" rule that some ldiscs rely on.

This avoids the

BUG: sleeping function called from invalid context at kernel/printk/printk.c:2659

when N_GSM has been attached to a virtual console, and gsmld_write()
calls con_write() while holding a spinlock, and con_write() then tries
to get the console lock.

Tested-by: Tetsuo Handa <[email protected]>
Cc: Jiri Slaby <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Daniel Starke <[email protected]>
Reported-by: syzbot <[email protected]>
Closes: https://syzkaller.appspot.com/bug?extid=dbac96d8e73b61aa559c
Signed-off-by: Linus Torvalds <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: tty_ldisc: Remove the ret variable

The int variable ret does not receive the return value in this function.
It should be removed and returned 0 directly.

Signed-off-by: Li zeming <zeming@nfsch

tty: tty_ldisc: Remove the ret variable

The int variable ret does not receive the return value in this function.
It should be removed and returned 0 directly.

Signed-off-by: Li zeming <[email protected]>
Reviewed-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: Move sysctl setup into "core" tty logic

In preparation for adding another sysctl to the tty subsystem, move the
tty setup code into the "core" tty code, which contains tty_init() itself.

Cc: G

tty: Move sysctl setup into "core" tty logic

In preparation for adding another sysctl to the tty subsystem, move the
tty setup code into the "core" tty code, which contains tty_init() itself.

Cc: Greg Kroah-Hartman <[email protected]>
Cc: Jiri Slaby <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: reformat kernel-doc in tty_ldisc.c

Kernel-doc is a bit strict about some formatting. So fix these:
1) When there is a tab in comments, it thinks the line is a continuation
one. So the descri

tty: reformat kernel-doc in tty_ldisc.c

Kernel-doc is a bit strict about some formatting. So fix these:
1) When there is a tab in comments, it thinks the line is a continuation
one. So the description of the functions end up as descriptions of
the last parameter described. Remove the tabs.

2) Remove newlines before parameters description and after the comments.
This was not wrong per se, only inconsistent with the rest of the
file.

3) Add periods to the end of sentences where appropriate.

4) Add "()" to function names and "%" to constants, so that they are
properly highlighted.

Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: unexport tty_ldisc_release

Initially, tty_ldisc_release() was exported for speakup (spk_tty) while
in staging. Later, the call to this function was removed as it was bogus
anyway.

Remove the e

tty: unexport tty_ldisc_release

Initially, tty_ldisc_release() was exported for speakup (spk_tty) while
in staging. Later, the call to this function was removed as it was bogus
anyway.

Remove the export now.

Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: unexport tty_ldisc_release

Initially, tty_ldisc_release() was exported for speakup (spk_tty) while
in staging. Later, the call to this function was removed as it was bogus
anyway.

Remove the e

tty: unexport tty_ldisc_release

Initially, tty_ldisc_release() was exported for speakup (spk_tty) while
in staging. Later, the call to this function was removed as it was bogus
anyway.

Remove the export now.

Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: tty_ldisc: fix doc warnings in tty_ldisc.c

Fixes the following W=1 kernel build warning(s):

drivers/tty/tty_ldisc.c:63: warning: Excess function
parameter 'disc' description in 'tty_registe

tty: tty_ldisc: fix doc warnings in tty_ldisc.c

Fixes the following W=1 kernel build warning(s):

drivers/tty/tty_ldisc.c:63: warning: Excess function
parameter 'disc' description in 'tty_register_ldisc'
drivers/tty/tty_ldisc.c:90: warning: Function parameter or
member 'ldisc' not described in 'tty_unregister_ldisc'
drivers/tty/tty_ldisc.c:90: warning: Excess function
parameter 'disc' description in 'tty_unregister_ldisc'

Signed-off-by: Baokun Li <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: return void from tty_unregister_ldisc

Now that noone checks the return value of tty_unregister_ldisc, make the
function return 'void'.

Signed-off-by: Jiri Slaby <[email protected]>
Link: https://

tty: return void from tty_unregister_ldisc

Now that noone checks the return value of tty_unregister_ldisc, make the
function return 'void'.

Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: drop tty_ldisc_ops::refcount

The refcount is checked only in tty_unregister_ldisc and EBUSY returned
if it is nonzero. But none of the tty_unregister_ldisc callers act
anyhow if this (or any ot

tty: drop tty_ldisc_ops::refcount

The refcount is checked only in tty_unregister_ldisc and EBUSY returned
if it is nonzero. But none of the tty_unregister_ldisc callers act
anyhow if this (or any other) error is returned. So remove
tty_ldisc_ops::refcount completely and make tty_unregister_ldisc return
'void' in the next patches. That means we assume tty_unregister_ldisc is
not called while the ldisc might be in use. That relies on
try_module_get in get_ldops and module_put in put_ldops.

Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: make tty_ldisc_ops a param in tty_unregister_ldisc

Make tty_unregister_ldisc symmetric to tty_register_ldisc by accepting
struct tty_ldisc_ops as a parameter instead of ldisc number. This avoid

tty: make tty_ldisc_ops a param in tty_unregister_ldisc

Make tty_unregister_ldisc symmetric to tty_register_ldisc by accepting
struct tty_ldisc_ops as a parameter instead of ldisc number. This avoids
checking of the ldisc number bounds in tty_unregister_ldisc.

Signed-off-by: Jiri Slaby <[email protected]>
Cc: William Hubbs <[email protected]>
Cc: Chris Brannon <[email protected]>
Cc: Kirk Reiser <[email protected]>
Cc: Samuel Thibault <[email protected]>
Cc: Marcel Holtmann <[email protected]>
Cc: Johan Hedberg <[email protected]>
Cc: Luiz Augusto von Dentz <[email protected]>
Cc: Dmitry Torokhov <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Wolfgang Grandegger <[email protected]>
Cc: Marc Kleine-Budde <[email protected]>
Cc: Andreas Koensgen <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Rodolfo Giometti <[email protected]>
Cc: Peter Ujfalusi <[email protected]>
Cc: Liam Girdwood <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Jaroslav Kysela <[email protected]>
Cc: Takashi Iwai <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: set tty_ldisc_ops::num statically

There is no reason to pass the ldisc number to tty_register_ldisc
separately. Just set it in the already defined tty_ldisc_ops in all the
ldiscs.

This simplif

tty: set tty_ldisc_ops::num statically

There is no reason to pass the ldisc number to tty_register_ldisc
separately. Just set it in the already defined tty_ldisc_ops in all the
ldiscs.

This simplifies tty_register_ldisc a bit too (no need to set the num
member there).

Signed-off-by: Jiri Slaby <[email protected]>
Cc: William Hubbs <[email protected]>
Cc: Chris Brannon <[email protected]>
Cc: Kirk Reiser <[email protected]>
Cc: Samuel Thibault <[email protected]>
Cc: Marcel Holtmann <[email protected]>
Cc: Johan Hedberg <[email protected]>
Cc: Luiz Augusto von Dentz <[email protected]>
Cc: Dmitry Torokhov <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Wolfgang Grandegger <[email protected]>
Cc: Marc Kleine-Budde <[email protected]>
Cc: Andreas Koensgen <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Rodolfo Giometti <[email protected]>
Cc: Peter Ujfalusi <[email protected]>
Cc: Liam Girdwood <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Jaroslav Kysela <[email protected]>
Cc: Takashi Iwai <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: create internal tty.h file

There are a number of functions and #defines in include/linux/tty.h that
do not belong there as they are private to the tty core code.

Create an initial drivers/tty/

tty: create internal tty.h file

There are a number of functions and #defines in include/linux/tty.h that
do not belong there as they are private to the tty core code.

Create an initial drivers/tty/tty.h file and copy the odd "tty logging"
macros into it to seed the file with some initial things that we know
nothing outside of the tty core should be calling.

Cc: Tetsuo Handa <[email protected]>
Cc: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: tty_ldisc: Remove the repeated word 'the'

Remove the repeated word 'the' following advice of checkpatch.pl

Signed-off-by: Xiaofei Tan <[email protected]>
Link: https://lore.kernel.org/r/16

tty: tty_ldisc: Remove the repeated word 'the'

Remove the repeated word 'the' following advice of checkpatch.pl

Signed-off-by: Xiaofei Tan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty: tty_ldisc: Do not use assignment in if condition

Do not use assignment in if condition following the advice of
checkpatch.pl.

Signed-off-by: Xiaofei Tan <[email protected]>
Link: https://l

tty: tty_ldisc: Do not use assignment in if condition

Do not use assignment in if condition following the advice of
checkpatch.pl.

Signed-off-by: Xiaofei Tan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: tty_ldisc: Fix coding style issues of block comments

Fix coding style issues of block comments, reported by checkpatch.pl.

Signed-off-by: Xiaofei Tan <[email protected]>
Link: https://lore

tty: tty_ldisc: Fix coding style issues of block comments

Fix coding style issues of block comments, reported by checkpatch.pl.

Signed-off-by: Xiaofei Tan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: tty_ldisc: Add a blank line after declarations

Add a blank line after declarations, reported by checkpatch.pl.

Signed-off-by: Xiaofei Tan <[email protected]>
Link: https://lore.kernel.org/

tty: tty_ldisc: Add a blank line after declarations

Add a blank line after declarations, reported by checkpatch.pl.

Signed-off-by: Xiaofei Tan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: tty_ldisc: Fix an issue of code indent should use tabs

Fix an issue of code indent should use tabs, reported by checkpatch.pl.

Signed-off-by: Xiaofei Tan <[email protected]>
Link: https://

tty: tty_ldisc: Fix an issue of code indent should use tabs

Fix an issue of code indent should use tabs, reported by checkpatch.pl.

Signed-off-by: Xiaofei Tan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: tty_ldisc: Fix some kernel-doc related misdemeanours

- Functions must follow directly on from their headers
- Demote non-conforming kernel-doc header
- Ensure notes have unique section names

tty: tty_ldisc: Fix some kernel-doc related misdemeanours

- Functions must follow directly on from their headers
- Demote non-conforming kernel-doc header
- Ensure notes have unique section names
- Provide missing description for 'reinit'

Fixes the following W=1 kernel build warning(s):

drivers/tty/tty_ldisc.c:158: warning: cannot understand function prototype: 'int tty_ldisc_autoload = IS_BUILTIN(CONFIG_LDISC_AUTOLOAD); '
drivers/tty/tty_ldisc.c:199: warning: Function parameter or member 'ld' not described in 'tty_ldisc_put'
drivers/tty/tty_ldisc.c:260: warning: duplicate section name 'Note'
drivers/tty/tty_ldisc.c:717: warning: Function parameter or member 'reinit' not described in 'tty_ldisc_hangup'

Cc: Greg Kroah-Hartman <[email protected]>
Cc: Jiri Slaby <[email protected]>
Signed-off-by: Lee Jones <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: tty_ldisc: Supply missing description for 'tty_ldisc_get's 'tty' param

Fixes the following W=1 kernel build warning(s):

drivers/tty/tty_ldisc.c:160: warning: Function parameter or member 'tty

tty: tty_ldisc: Supply missing description for 'tty_ldisc_get's 'tty' param

Fixes the following W=1 kernel build warning(s):

drivers/tty/tty_ldisc.c:160: warning: Function parameter or member 'tty' not described in 'tty_ldisc_get'

Cc: Greg Kroah-Hartman <[email protected]>
Cc: Jiri Slaby <[email protected]>
Signed-off-by: Lee Jones <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

tty: fix kernel-doc

With W=1, the kernel-doc checker complains quite a lot in the tty layer.
Over the time, many documented parameters were renamed, removed or
switched from tty to tty_port and simi

tty: fix kernel-doc

With W=1, the kernel-doc checker complains quite a lot in the tty layer.
Over the time, many documented parameters were renamed, removed or
switched from tty to tty_port and similar. Some were mistyped in the doc
too.

So fix all these in the tty core. (But do not add the missing ones which
the checker complains about too. Not now.) The rest in the tty layer
will follow in the next patches.

Signed-off-by: Jiri Slaby <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty_ldisc: simplify tty_ldisc_autoload initialization

We have got existing macro to check for CONFIG option, use it.

Signed-off-by: Pavel Machek <[email protected]>

Link: https://lore.kernel.org/r/201

tty_ldisc: simplify tty_ldisc_autoload initialization

We have got existing macro to check for CONFIG option, use it.

Signed-off-by: Pavel Machek <[email protected]>

Link: https://lore.kernel.org/r/20190924083244.GA4344@amd
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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proc/sysctl: add shared variables for range check

In the sysctl code the proc_dointvec_minmax() function is often used to
validate the user supplied value between an allowed range. This
function us

proc/sysctl: add shared variables for range check

In the sysctl code the proc_dointvec_minmax() function is often used to
validate the user supplied value between an allowed range. This
function uses the extra1 and extra2 members from struct ctl_table as
minimum and maximum allowed value.

On sysctl handler declaration, in every source file there are some
readonly variables containing just an integer which address is assigned
to the extra1 and extra2 members, so the sysctl range is enforced.

The special values 0, 1 and INT_MAX are very often used as range
boundary, leading duplication of variables like zero=0, one=1,
int_max=INT_MAX in different source files:

$ git grep -E '\.extra[12].*&(zero|one|int_max)' |wc -l
248

Add a const int array containing the most commonly used values, some
macros to refer more easily to the correct array member, and use them
instead of creating a local one for every object file.

This is the bloat-o-meter output comparing the old and new binary
compiled with the default Fedora config:

# scripts/bloat-o-meter -d vmlinux.o.old vmlinux.o
add/remove: 2/2 grow/shrink: 0/2 up/down: 24/-188 (-164)
Data old new delta
sysctl_vals - 12 +12
__kstrtab_sysctl_vals - 12 +12
max 14 10 -4
int_max 16 - -16
one 68 - -68
zero 128 28 -100
Total: Before=20583249, After=20583085, chg -0.00%

[[email protected]: tipc: remove two unused variables]
Link: http://lkml.kernel.org/r/[email protected]
[[email protected]: fix net/ipv6/sysctl_net_ipv6.c]
[[email protected]: proc/sysctl: make firmware loader table conditional]
Link: http://lkml.kernel.org/r/[email protected]
[[email protected]: fix fs/eventpoll.c]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Matteo Croce <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
Acked-by: Kees Cook <[email protected]>
Reviewed-by: Aaron Tomlin <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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locking/lockdep: Rename lockdep_assert_held_exclusive() -> lockdep_assert_held_write()

All callers of lockdep_assert_held_exclusive() use it to verify the
correct locking state of either a semaphore

locking/lockdep: Rename lockdep_assert_held_exclusive() -> lockdep_assert_held_write()

All callers of lockdep_assert_held_exclusive() use it to verify the
correct locking state of either a semaphore (ldisc_sem in tty,
mmap_sem for perf events, i_rwsem of inode for dax) or rwlock by
apparmor. Thus it makes sense to rename _exclusive to _write since
that's the semantics callers care. Additionally there is already
lockdep_assert_held_read(), which this new naming is more consistent with.

No functional changes.

Signed-off-by: Nikolay Borisov <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

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tty: ldisc: add sysctl to prevent autoloading of ldiscs

By default, the kernel will automatically load the module of any line
dicipline that is asked for. As this sometimes isn't the safest thing
t

tty: ldisc: add sysctl to prevent autoloading of ldiscs

By default, the kernel will automatically load the module of any line
dicipline that is asked for. As this sometimes isn't the safest thing
to do, provide a sysctl to disable this feature.

By default, we set this to 'y' as that is the historical way that Linux
has worked, and we do not want to break working systems. But in the
future, perhaps this can default to 'n' to prevent this functionality.

Signed-off-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Theodore Ts'o <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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tty/ldsem: Add lockdep asserts for ldisc_sem

Make sure under CONFIG_LOCKDEP that each change to line discipline
is done with held write semaphor.
Otherwise potential reader will have a good time der

tty/ldsem: Add lockdep asserts for ldisc_sem

Make sure under CONFIG_LOCKDEP that each change to line discipline
is done with held write semaphor.
Otherwise potential reader will have a good time dereferencing
incomplete/uninitialized ldisc.

An exception here is tty_ldisc_open(), as it's called without ldisc_sem
locked by tty_init_dev() => tty_ldisc_setup() for the tty->link.

It seem valid as tty_init_dev() will call tty_driver_install_tty()
which will find ops->install(). Install will establish tty->link in
pty_common_install(), just after allocation of slave tty with
alloc_tty_struct(). So, no one should have a reference to slave pty yet.

Cc: Jiri Slaby <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Signed-off-by: Dmitry Safonov <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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