linux-kernel - Re: [PATCH v4 4/4] locking/lockdep: Add kasan_check_byte() check in lock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CANpmjNM-uN81Aje1GE9zgUW-Q=w_2gPQ28giO7N2nmbRM521kA@mail.gmail.com>
Date: Fri, 14 Feb 2025 11:44:24 +0100
From: Marco Elver <elver@...gle.com>
To: Waiman Long <longman@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Will Deacon <will.deacon@....com>, Boqun Feng <boqun.feng@...il.com>, 
	Andrey Ryabinin <ryabinin.a.a@...il.com>, Alexander Potapenko <glider@...gle.com>, 
	Andrey Konovalov <andreyknvl@...il.com>, Dmitry Vyukov <dvyukov@...gle.com>, 
	Vincenzo Frascino <vincenzo.frascino@....com>, linux-kernel@...r.kernel.org, 
	kasan-dev@...glegroups.com
Subject: Re: [PATCH v4 4/4] locking/lockdep: Add kasan_check_byte() check in lock_acquire()

On Thu, 13 Feb 2025 at 21:02, Waiman Long <longman@...hat.com> wrote:
>
> KASAN instrumentation of lockdep has been disabled as we don't need
> KASAN to check the validity of lockdep internal data structures and
> incur unnecessary performance overhead. However, the lockdep_map pointer
> passed in externally may not be valid (e.g. use-after-free) and we run
> the risk of using garbage data resulting in false lockdep reports. Add
> kasan_check_byte() call in lock_acquire() for non kernel core data
> object to catch invalid lockdep_map and abort lockdep processing if
> input data isn't valid.
>
> Suggested-by: Marco Elver <elver@...gle.com>
> Signed-off-by: Waiman Long <longman@...hat.com>

Reviewed-by: Marco Elver <elver@...gle.com>

but double-check if the below can be simplified.

> ---
>  kernel/locking/lock_events_list.h |  1 +
>  kernel/locking/lockdep.c          | 14 ++++++++++++++
>  2 files changed, 15 insertions(+)
>
> diff --git a/kernel/locking/lock_events_list.h b/kernel/locking/lock_events_list.h
> index 9ef9850aeebe..bed59b2195c7 100644
> --- a/kernel/locking/lock_events_list.h
> +++ b/kernel/locking/lock_events_list.h
> @@ -95,3 +95,4 @@ LOCK_EVENT(rtmutex_deadlock)  /* # of rt_mutex_handle_deadlock()'s    */
>  LOCK_EVENT(lockdep_acquire)
>  LOCK_EVENT(lockdep_lock)
>  LOCK_EVENT(lockdep_nocheck)
> +LOCK_EVENT(lockdep_kasan_fail)
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index 8436f017c74d..98dd0455d4be 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -57,6 +57,7 @@
>  #include <linux/lockdep.h>
>  #include <linux/context_tracking.h>
>  #include <linux/console.h>
> +#include <linux/kasan.h>
>
>  #include <asm/sections.h>
>
> @@ -5830,6 +5831,19 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
>         if (!debug_locks)
>                 return;
>
> +       /*
> +        * As KASAN instrumentation is disabled and lock_acquire() is usually
> +        * the first lockdep call when a task tries to acquire a lock, add
> +        * kasan_check_byte() here to check for use-after-free of non kernel
> +        * core lockdep_map data to avoid referencing garbage data.
> +        */
> +       if (unlikely(IS_ENABLED(CONFIG_KASAN) &&

This is not needed - kasan_check_byte() will always return true if
KASAN is disabled or not compiled in.

> +                    !is_kernel_core_data((unsigned long)lock) &&

Why use !is_kernel_core_data()? Is it to improve performance?

> +                    !kasan_check_byte(lock))) {
> +               lockevent_inc(lockdep_kasan_fail);
> +               return;
> +       }
> +
>         if (unlikely(!lockdep_enabled())) {
>                 /* XXX allow trylock from NMI ?!? */
>                 if (lockdep_nmi() && !trylock) {
> --
> 2.48.1
>
> --
> You received this message because you are subscribed to the Google Groups "kasan-dev" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@...glegroups.com.
> To view this discussion visit https://groups.google.com/d/msgid/kasan-dev/20250213200228.1993588-5-longman%40redhat.com.