linux.git/samples/livepatch/livepatch-shadow-fix1.c, branch v6.18.21

samples/livepatch: add module descriptions

2025-04-12T00:32:38+00:00

Every module should have a description, so add one for each of these modules.

[akpm@linux-foundation.org: match the livepatch-callbacks-mod.c description, per Petr]
Link: https://lkml.kernel.org/r/20250324173242.1501003-3-arnd@kernel.org
Fixes: 6c6c1fc09de3 ("modpost: require a MODULE_DESCRIPTION()")
Signed-off-by: Arnd Bergmann 
Reviewed-by: Petr Mladek 
Cc: Christophe Leroy 
Cc: Easwar Hariharan 
Cc: Jeff Johnson 
Cc: Jiri Kosina 
Cc: Joe Lawrence 
Cc: Josh Poimboeuf 
Cc: Masahiro Yamada 
Cc: Miroslav Benes 
Cc: Stehen Rothwell 
Signed-off-by: Andrew Morton

livepatch: convert timeouts to secs_to_jiffies()

2025-01-13T04:21:05+00:00

Commit b35108a51cf7 ("jiffies: Define secs_to_jiffies()") introduced
secs_to_jiffies().  As the value here is a multiple of 1000, use
secs_to_jiffies() instead of msecs_to_jiffies to avoid the multiplication.

This is converted using scripts/coccinelle/misc/secs_to_jiffies.cocci with
the following Coccinelle rules:

@@ constant C; @@

- msecs_to_jiffies(C * 1000)
+ secs_to_jiffies(C)

@@ constant C; @@

- msecs_to_jiffies(C * MSEC_PER_SEC)
+ secs_to_jiffies(C)

Link: https://lkml.kernel.org/r/20241210-converge-secs-to-jiffies-v3-18-ddfefd7e9f2a@linux.microsoft.com
Signed-off-by: Easwar Hariharan 
Reviewed-by: Christophe Leroy 
Cc: Alexander Gordeev 
Cc: Andrew Lunn 
Cc: Anna-Maria Behnsen 
Cc: Catalin Marinas 
Cc: Christian Borntraeger 
Cc: Daniel Mack 
Cc: David Airlie 
Cc: David S. Miller 
Cc: Dick Kennedy 
Cc: Eric Dumazet 
Cc: Florian Fainelli 
Cc: Greg Kroah-Hartman 
Cc: Haojian Zhuang 
Cc: Heiko Carstens 
Cc: Ilya Dryomov 
Cc: Jack Wang 
Cc: Jakub Kicinski 
Cc: James Bottomley 
Cc: James Smart 
Cc: Jaroslav Kysela 
Cc: Jeff Johnson 
Cc: Jeff Johnson 
Cc: Jens Axboe 
Cc: Jeroen de Borst 
Cc: Jiri Kosina 
Cc: Joe Lawrence 
Cc: Johan Hedberg 
Cc: Josh Poimboeuf 
Cc: Jozsef Kadlecsik 
Cc: Julia Lawall 
Cc: Kalle Valo 
Cc: Louis Peens 
Cc: Lucas De Marchi 
Cc: Luiz Augusto von Dentz 
Cc: Maarten Lankhorst 
Cc: Madhavan Srinivasan 
Cc: Marcel Holtmann 
Cc: Martin K. Petersen 
Cc: Maxime Ripard 
Cc: Michael Ellerman 
Cc: Miroslav Benes 
Cc: Naveen N Rao 
Cc: Nicholas Piggin 
Cc: Nicolas Palix 
Cc: Oded Gabbay 
Cc: Ofir Bitton 
Cc: Pablo Neira Ayuso 
Cc: Paolo Abeni 
Cc: Petr Mladek 
Cc: Praveen Kaligineedi 
Cc: Ray Jui 
Cc: Robert Jarzmik 
Cc: Rodrigo Vivi 
Cc: Roger Pau Monné 
Cc: Russell King 
Cc: Scott Branden 
Cc: Shailend Chand 
Cc: Simona Vetter 
Cc: Simon Horman 
Cc: Sven Schnelle 
Cc: Takashi Iwai 
Cc: Thomas Hellström 
Cc: Thomas Zimmermann 
Cc: Vasily Gorbik 
Cc: Xiubo Li 
Signed-off-by: Andrew Morton

livepatch: Reorder to use before freeing a pointer

2022-03-23T12:51:11+00:00

Clang static analysis reports this issue
livepatch-shadow-fix1.c:113:2: warning: Use of
  memory after it is freed
  pr_info("%s: dummy @ %p, prevented leak @ %p\n",
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The pointer is freed in the previous statement.
Reorder the pr_info to report before the free.

Similar issue in livepatch-shadow-fix2.c

Note that it is a false positive. pr_info() just prints the address.
The freed memory is not accessed. Well, the static analyzer could not
know this easily.

Signed-off-by: Tom Rix 
Reviewed-by: Petr Mladek 
Acked-by: David Vernet 
Acked-by: Joe Lawrence 
[pmladek@suse.com: Note about that it was false positive.]
Signed-off-by: Petr Mladek 
Link: https://lore.kernel.org/r/20220320015143.2208591-1-trix@redhat.com

livepatch: Handle allocation failure in the sample of shadow variable API

2020-01-17T10:12:06+00:00

klp_shadow_alloc() is not handled in the sample of shadow variable API.
It is not strictly necessary because livepatch_fix1_dummy_free() is
able to handle the potential failure. But it is an example and it should
use the API a clean way.

Signed-off-by: Petr Mladek 
Reviewed-by: Joe Lawrence 
Acked-by: Miroslav Benes 
Reviewed-by: Kamalesh Babulal 
Signed-off-by: Jiri Kosina

livepatch/samples/selftest: Use klp_shadow_alloc() API correctly

2020-01-17T10:12:06+00:00

The commit e91c2518a5d22a ("livepatch: Initialize shadow variables
safely by a custom callback") leads to the following static checker
warning:

  samples/livepatch/livepatch-shadow-fix1.c:86 livepatch_fix1_dummy_alloc()
  error: 'klp_shadow_alloc()' 'leak' too small (4 vs 8)

It is because klp_shadow_alloc() is used a wrong way:

  int *leak;
  shadow_leak = klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL,
				 shadow_leak_ctor, leak);

The code is supposed to store the "leak" pointer into the shadow variable.
3rd parameter correctly passes size of the data (size of pointer). But
the 5th parameter is wrong. It should pass pointer to the data (pointer
to the pointer) but it passes the pointer directly.

It works because shadow_leak_ctor() handle "ctor_data" as the data
instead of pointer to the data. But it is semantically wrong and
confusing.

The same problem is also in the module used by selftests. In this case,
"pvX" variables are introduced. They represent the data stored in
the shadow variables.

Reported-by: Dan Carpenter 
Signed-off-by: Petr Mladek 
Reviewed-by: Joe Lawrence 
Acked-by: Miroslav Benes 
Reviewed-by: Kamalesh Babulal 
Signed-off-by: Jiri Kosina

livepatch/sample: Use the right type for the leaking data pointer

2020-01-17T10:12:06+00:00

The "leak" pointer, in the sample of shadow variable API, is allocated
as sizeof(int). Let's help developers and static analyzers with
understanding the code by using the appropriate pointer type.

Reported-by: Dan Carpenter 
Signed-off-by: Petr Mladek 
Reviewed-by: Joe Lawrence 
Acked-by: Miroslav Benes 
Reviewed-by: Kamalesh Babulal 
Signed-off-by: Jiri Kosina

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13

2019-05-21T09:28:45+00:00

Based on 2 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 see http www gnu org licenses

  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 [based]
  [from] [clk] [highbank] [c] you should have received a copy of the
  gnu general public license along with this program if not see http
  www gnu org licenses

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 355 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Kate Stewart 
Reviewed-by: Jilayne Lovejoy 
Reviewed-by: Steve Winslow 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190519154041.837383322@linutronix.de
Signed-off-by: Greg Kroah-Hartman

Merge branch 'for-5.0/upstream-fixes' into for-linus

2019-03-05T14:55:59+00:00

Document change towards group maintainership of livepatching code
samples/ warning fix from Nicholas Mc Guire

livepatch: samples: non static warnings fix

2019-01-25T15:43:35+00:00

Sparse reported warnings about non-static symbols. For the variables
a simple static attribute is fine - for the functions referenced by
livepatch via klp_func the symbol-names must be unmodified in the
symbol table and the patchable code has to be emitted. The resolution
is to attach __used attribute to the shared statically declared functions.

Link: https://lore.kernel.org/lkml/1544965657-26804-1-git-send-email-hofrat@osadl.org/
Suggested-by: Joe Lawrence 
Signed-off-by: Nicholas Mc Guire 
Acked-by: Miroslav Benes 
Signed-off-by: Jiri Kosina

livepatch: Simplify API by removing registration step

2019-01-11T19:51:24+00:00

The possibility to re-enable a registered patch was useful for immediate
patches where the livepatch module had to stay until the system reboot.
The improved consistency model allows to achieve the same result by
unloading and loading the livepatch module again.

Also we are going to add a feature called atomic replace. It will allow
to create a patch that would replace all already registered patches.
The aim is to handle dependent patches more securely. It will obsolete
the stack of patches that helped to handle the dependencies so far.
Then it might be unclear when a cumulative patch re-enabling is safe.

It would be complicated to support the many modes. Instead we could
actually make the API and code easier to understand.

Therefore, remove the two step public API. All the checks and init calls
are moved from klp_register_patch() to klp_enabled_patch(). Also the patch
is automatically freed, including the sysfs interface when the transition
to the disabled state is completed.

As a result, there is never a disabled patch on the top of the stack.
Therefore we do not need to check the stack in __klp_enable_patch().
And we could simplify the check in __klp_disable_patch().

Also the API and logic is much easier. It is enough to call
klp_enable_patch() in module_init() call. The patch can be disabled
by writing '0' into /sys/kernel/livepatch//enabled. Then the module
can be removed once the transition finishes and sysfs interface is freed.

The only problem is how to free the structures and kobjects safely.
The operation is triggered from the sysfs interface. We could not put
the related kobject from there because it would cause lock inversion
between klp_mutex and kernfs locks, see kn->count lockdep map.

Therefore, offload the free task to a workqueue. It is perfectly fine:

  + The patch can no longer be used in the livepatch operations.

  + The module could not be removed until the free operation finishes
    and module_put() is called.

  + The operation is asynchronous already when the first
    klp_try_complete_transition() fails and another call
    is queued with a delay.

Suggested-by: Josh Poimboeuf 
Signed-off-by: Petr Mladek 
Acked-by: Miroslav Benes 
Acked-by: Josh Poimboeuf 
Signed-off-by: Jiri Kosina