pps: Fix a use-after-free

On a board running ntpd and gpsd, I'm seeing a consistent use-after-free
in sys_exit() from gpsd when rebooting:

pps pps1: removed
------------[ cut here ]--------

pps: Fix a use-after-free

On a board running ntpd and gpsd, I'm seeing a consistent use-after-free
in sys_exit() from gpsd when rebooting:

pps pps1: removed
------------[ cut here ]------------
kobject: '(null)' (00000000db4bec24): is not initialized, yet kobject_put() is being called.
WARNING: CPU: 2 PID: 440 at lib/kobject.c:734 kobject_put+0x120/0x150
CPU: 2 UID: 299 PID: 440 Comm: gpsd Not tainted 6.11.0-rc6-00308-gb31c44928842 #1
Hardware name: Raspberry Pi 4 Model B Rev 1.1 (DT)
pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : kobject_put+0x120/0x150
lr : kobject_put+0x120/0x150
sp : ffffffc0803d3ae0
x29: ffffffc0803d3ae0 x28: ffffff8042dc9738 x27: 0000000000000001
x26: 0000000000000000 x25: ffffff8042dc9040 x24: ffffff8042dc9440
x23: ffffff80402a4620 x22: ffffff8042ef4bd0 x21: ffffff80405cb600
x20: 000000000008001b x19: ffffff8040b3b6e0 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000 x15: 696e6920746f6e20
x14: 7369203a29343263 x13: 205d303434542020 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
kobject_put+0x120/0x150
cdev_put+0x20/0x3c
__fput+0x2c4/0x2d8
____fput+0x1c/0x38
task_work_run+0x70/0xfc
do_exit+0x2a0/0x924
do_group_exit+0x34/0x90
get_signal+0x7fc/0x8c0
do_signal+0x128/0x13b4
do_notify_resume+0xdc/0x160
el0_svc+0xd4/0xf8
el0t_64_sync_handler+0x140/0x14c
el0t_64_sync+0x190/0x194
---[ end trace 0000000000000000 ]---

...followed by more symptoms of corruption, with similar stacks:

refcount_t: underflow; use-after-free.
kernel BUG at lib/list_debug.c:62!
Kernel panic - not syncing: Oops - BUG: Fatal exception

This happens because pps_device_destruct() frees the pps_device with the
embedded cdev immediately after calling cdev_del(), but, as the comment
above cdev_del() notes, fops for previously opened cdevs are still
callable even after cdev_del() returns. I think this bug has always
been there: I can't explain why it suddenly started happening every time
I reboot this particular board.

In commit d953e0e837e6 ("pps: Fix a use-after free bug when
unregistering a source."), George Spelvin suggested removing the
embedded cdev. That seems like the simplest way to fix this, so I've
implemented his suggestion, using __register_chrdev() with pps_idr
becoming the source of truth for which minor corresponds to which
device.

But now that pps_idr defines userspace visibility instead of cdev_add(),
we need to be sure the pps->dev refcount can't reach zero while
userspace can still find it again. So, the idr_remove() call moves to
pps_unregister_cdev(), and pps_idr now holds a reference to pps->dev.

pps_core: source serial1 got cdev (251:1)
<...>
pps pps1: removed
pps_core: unregistering pps1
pps_core: deallocating pps1

Fixes: d953e0e837e6 ("pps: Fix a use-after free bug when unregistering a source.")
Cc: [email protected]
Signed-off-by: Calvin Owens <[email protected]>
Reviewed-by: Michal Schmidt <[email protected]>
Link: https://lore.kernel.org/r/a17975fd5ae99385791929e563f72564edbcf28f.1731383727.git.calvin@wbinvd.org
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 61

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not write to the free software foundation inc
675 mass ave cambridge ma 02139 usa

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 441 file(s).

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Michael Ellerman <[email protected]> (powerpc)
Reviewed-by: Richard Fontana <[email protected]>
Reviewed-by: Allison Randal <[email protected]>
Reviewed-by: Kate Stewart <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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pps: using ERR_PTR instead of NULL while pps_register_source fails

pps_register_source() has keeps error codes in a local variable,
but it does not make use of the code. This patch let it return
the

pps: using ERR_PTR instead of NULL while pps_register_source fails

pps_register_source() has keeps error codes in a local variable,
but it does not make use of the code. This patch let it return
the errcode in case of failure.

Suggested-by: Richard Cochran <[email protected]>
Signed-off-by: YueHaibing <[email protected]>
Acked-by: Rodolfo Giometti <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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ntp/pps: use y2038 safe types in pps_event_time

The pps_event_time uses two 'timespec' structures internally, which
suffer from the y2038 problem. The uses of this structure are
fairly self-containe

ntp/pps: use y2038 safe types in pps_event_time

The pps_event_time uses two 'timespec' structures internally, which
suffer from the y2038 problem. The uses of this structure are
fairly self-contained in the pps code, so this replaces them all at
once.

Unfortunately, this includes the sfc ethernet driver aside from the
pps subsystem, so we change that one as well. Both touch the
same data structure, and there probably is no good way to split
the patch into smaller units.

Acked-by: Richard Cochran <[email protected]>
Acked-by: David S. Miller <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Arnd Bergmann <[email protected]>
Signed-off-by: John Stultz <[email protected]>

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pps: convert to idr_alloc()

Convert to the much saner new idr interface.

Signed-off-by: Tejun Heo <[email protected]>
Cc: Rodolfo Giometti <[email protected]>
Signed-off-by: Andrew Morton <akpm@lin

pps: convert to idr_alloc()

Convert to the much saner new idr interface.

Signed-off-by: Tejun Heo <[email protected]>
Cc: Rodolfo Giometti <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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pps: default echo function

A default echo function has been provided so it is no longer an error when
you specify PPS_ECHOASSERT or PPS_ECHOCLEAR without an explicit echo
function. This allows some

pps: default echo function

A default echo function has been provided so it is no longer an error when
you specify PPS_ECHOASSERT or PPS_ECHOCLEAR without an explicit echo
function. This allows some code re-use and also makes it easier to write
client drivers since the default echo function does not normally need to
change.

Signed-off-by: James Nuss <[email protected]>
Reviewed-by: Ben Gardiner <[email protected]>
Acked-by: Rodolfo Giometti <[email protected]>
Cc: Ricardo Martins <[email protected]>
Cc: Alexander Gordeev <[email protected]>
Cc: Igor Plyatov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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pps: initialize ts_real properly

Initialize ts_real.flags to fix compiler warning about possible
uninitialized use of this field.

Signed-off-by: Alexander Gordeev <[email protected]>
Cc: john s

pps: initialize ts_real properly

Initialize ts_real.flags to fix compiler warning about possible
uninitialized use of this field.

Signed-off-by: Alexander Gordeev <[email protected]>
Cc: john stultz <[email protected]>
Cc: Rodolfo Giometti <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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pps: add kernel consumer support

Add an optional feature of PPSAPI, kernel consumer support, which uses the
added hardpps() function.

Signed-off-by: Alexander Gordeev <[email protected]>
Acked-

pps: add kernel consumer support

Add an optional feature of PPSAPI, kernel consumer support, which uses the
added hardpps() function.

Signed-off-by: Alexander Gordeev <[email protected]>
Acked-by: Rodolfo Giometti <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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pps: simplify conditions a bit

Bitwise conjunction is distributive so we can simplify some conditions.

Signed-off-by: Alexander Gordeev <[email protected]>
Acked-by: Rodolfo Giometti <giometti@

pps: simplify conditions a bit

Bitwise conjunction is distributive so we can simplify some conditions.

Signed-off-by: Alexander Gordeev <[email protected]>
Acked-by: Rodolfo Giometti <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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pps: use BUG_ON for kernel API safety checks

This way less overhead is involved when running production kernel. If you
want to debug a pps client module please define DEBUG to enable the
checks.

S

pps: use BUG_ON for kernel API safety checks

This way less overhead is involved when running production kernel. If you
want to debug a pps client module please define DEBUG to enable the
checks.

Signed-off-by: Alexander Gordeev <[email protected]>
Acked-by: Rodolfo Giometti <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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pps: move idr stuff to pps.c

Since now idr is only used to manage char device id's and not used in
kernel API anymore it should be moved to pps.c. This also makes it
possible to release id only at

pps: move idr stuff to pps.c

Since now idr is only used to manage char device id's and not used in
kernel API anymore it should be moved to pps.c. This also makes it
possible to release id only at actual device freeing so nobody can
register a pps device with the same id while our device is not freed yet.

Signed-off-by: Alexander Gordeev <[email protected]>
Acked-by: Rodolfo Giometti <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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pps: convert printk/pr_* to dev_*

Since we now have direct pointers to struct pps_device everywhere it's
easy to use dev_* functions to print messages instead of plain printks.
Where dev_* cannot be

pps: convert printk/pr_* to dev_*

Since we now have direct pointers to struct pps_device everywhere it's
easy to use dev_* functions to print messages instead of plain printks.
Where dev_* cannot be used printks are converted to pr_*.

Signed-off-by: Alexander Gordeev <[email protected]>
Acked-by: Rodolfo Giometti <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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pps: access pps device by direct pointer

Using device index as a pointer needs some unnecessary work to be done
every time the pointer is needed (in irq handler for example). Using a
direct pointer

pps: access pps device by direct pointer

Using device index as a pointer needs some unnecessary work to be done
every time the pointer is needed (in irq handler for example). Using a
direct pointer is much more easy (and safe as well).

Signed-off-by: Alexander Gordeev <[email protected]>
Acked-by: Rodolfo Giometti <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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pps: unify timestamp gathering

Add a helper function to gather timestamps. This way clients don't have
to duplicate it.

Signed-off-by: Alexander Gordeev <[email protected]>
Acked-by: Rodolfo G

pps: unify timestamp gathering

Add a helper function to gather timestamps. This way clients don't have
to duplicate it.

Signed-off-by: Alexander Gordeev <[email protected]>
Acked-by: Rodolfo Giometti <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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pps: fix race in PPS_FETCH handler

There was a race in PPS_FETCH ioctl handler when several processes want to
obtain PPS data simultaneously using sleeping PPS_FETCH. They all sleep
most of the tim

pps: fix race in PPS_FETCH handler

There was a race in PPS_FETCH ioctl handler when several processes want to
obtain PPS data simultaneously using sleeping PPS_FETCH. They all sleep
most of the time in the system call.

With the old approach when the first process waiting on the pps queue is
waken up it makes new system call right away and zeroes pps->go. So other
processes continue to sleep. This is a clear race condition because of
the global 'go' variable.

With the new approach pps->last_ev holds some value increasing at each PPS
event. PPS_FETCH ioctl handler saves current value to the local variable
at the very beginning so it can safely check that there is a new event by
just comparing both variables.

Signed-off-by: Alexander Gordeev <[email protected]>
Acked-by: Rodolfo Giometti <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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pps: trivial fixes

Here are some very trivial fixes combined:

- add macro definitions to protect header file from including several times

- remove declaration for an unexistent array

- fix typos

pps: trivial fixes

Here are some very trivial fixes combined:

- add macro definitions to protect header file from including several times

- remove declaration for an unexistent array

- fix typos

Signed-off-by: Alexander Gordeev <[email protected]>
Acked-by: Rodolfo Giometti <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when bu

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.

2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).

* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <[email protected]>
Guess-its-ok-by: Christoph Lameter <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Lee Schermerhorn <[email protected]>

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pps: events reporting fix up

PPS events must be recorded according to PPS's mode settings.

If a process asks for (i.e.) capture-assert events only, when the PPS
client calls the pps_event() functio

pps: events reporting fix up

PPS events must be recorded according to PPS's mode settings.

If a process asks for (i.e.) capture-assert events only, when the PPS
client calls the pps_event() function to save the current PPS event, we
should verify the event type and then discard unwanted ones.

Also, without this patch userland processes waiting for a specific PPS
event (assert or clear but not both) may be awakened at wrong time.

Signed-off-by: Rodolfo Giometti <[email protected]>
Tested-by: William S. Brasher <[email protected]>
Tested-by: Reg Clemens <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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LinuxPPS: core support

This patch adds the kernel side of the PPS support currently named
"LinuxPPS".

PPS means "pulse per second" and a PPS source is just a device which
provides a high precision

LinuxPPS: core support

This patch adds the kernel side of the PPS support currently named
"LinuxPPS".

PPS means "pulse per second" and a PPS source is just a device which
provides a high precision signal each second so that an application can
use it to adjust system clock time.

Common use is the combination of the NTPD as userland program with a GPS
receiver as PPS source to obtain a wallclock-time with sub-millisecond
synchronisation to UTC.

To obtain this goal the userland programs shoud use the PPS API
specification (RFC 2783 - Pulse-Per-Second API for UNIX-like Operating
Systems, Version 1.0) which in part is implemented by this patch. It
provides a set of chars devices, one per PPS source, which can be used to
get the time signal. The RFC's functions can be implemented by accessing
to these char devices.

Signed-off-by: Rodolfo Giometti <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Greg KH <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Kay Sievers <[email protected]>
Acked-by: Alan Cox <[email protected]>
Cc: Michael Kerrisk <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Roman Zippel <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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