From: Kees Cook <keescook@chromium.org>
To: Shuah Khan <skhan@linuxfoundation.org>
Cc: shuah@kernel.org, gregkh@linuxfoundation.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v2 02/11] selftests:lib:test_counters: add new test for counters
Date: Wed, 7 Oct 2020 11:12:01 -0700 [thread overview]
Message-ID: <202010071111.F3968C04@keescook> (raw)
In-Reply-To: <dd751c3ecedef23f3bd12c043863a6233fceb0d9.1602011710.git.skhan@linuxfoundation.org>
On Tue, Oct 06, 2020 at 02:44:33PM -0600, Shuah Khan wrote:
> Add a new selftest for testing counter_atomic* Counters API. This test
> load test_counters test modules and unloads.
>
> The test module runs tests and prints results in dmesg.
>
> There are a number of atomic_t usages in the kernel where atomic_t api
> is used strictly for counting and not for managing object lifetime. In
> some cases, atomic_t might not even be needed.
>
> The purpose of these counters is to clearly differentiate atomic_t
> counters from atomic_t usages that guard object lifetimes, hence prone
> to overflow and underflow errors. It allows tools that scan for underflow
> and overflow on atomic_t usages to detect overflow and underflows to scan
> just the cases that are prone to errors.
>
> Simple atomic counters api provides interfaces for simple atomic counters
> that just count, and don't guard resource lifetimes. Counter will wrap
> around to 0 when it overflows and should not be used to guard resource
> lifetimes, device usage and open counts that control state changes, and
> pm states.
>
> Using counter_atomic* to guard lifetimes could lead to use-after free
> when it overflows and undefined behavior when used to manage state
> changes and device usage/open states.
>
> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
next prev parent reply other threads:[~2020-10-07 18:12 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-06 20:44 [PATCH v2 00/11] Introduce Simple atomic counters Shuah Khan
2020-10-06 20:44 ` [PATCH v2 01/11] counters: Introduce counter_atomic* counters Shuah Khan
2020-10-07 9:04 ` Greg KH
2020-10-08 17:18 ` Shuah Khan
2020-10-07 18:11 ` Kees Cook
2020-10-07 19:26 ` Shuah Khan
2020-10-07 20:30 ` Kees Cook
2020-10-06 20:44 ` [PATCH v2 02/11] selftests:lib:test_counters: add new test for counters Shuah Khan
2020-10-07 18:12 ` Kees Cook [this message]
2020-10-06 20:44 ` [PATCH v2 03/11] drivers/base: convert deferred_trigger_count and probe_count to counter_atomic32 Shuah Khan
2020-10-07 18:13 ` Kees Cook
2020-10-06 20:44 ` [PATCH v2 04/11] drivers/base/devcoredump: convert devcd_count " Shuah Khan
2020-10-07 18:15 ` Kees Cook
2020-10-07 19:33 ` Shuah Khan
2020-10-07 19:38 ` Johannes Berg
2020-10-07 19:59 ` Shuah Khan
2020-10-07 20:43 ` Kees Cook
2020-10-08 6:42 ` Johannes Berg
2020-10-08 7:37 ` Kees Cook
2020-10-06 20:44 ` [PATCH v2 05/11] drivers/acpi: convert seqno counter_atomic32 Shuah Khan
2020-10-07 18:16 ` Kees Cook
2020-10-06 20:44 ` [PATCH v2 06/11] drivers/acpi/apei: " Shuah Khan
2020-10-07 18:17 ` Kees Cook
2020-10-06 20:44 ` [PATCH v2 07/11] drivers/android/binder: convert stats, transaction_log to counter_atomic32 Shuah Khan
2020-10-07 18:18 ` Kees Cook
2020-10-09 12:39 ` Christian Brauner
2020-10-06 20:44 ` [PATCH v2 08/11] drivers/base/test/test_async_driver_probe: convert to use counter_atomic32 Shuah Khan
2020-10-07 18:20 ` Kees Cook
2020-10-06 20:44 ` [PATCH v2 09/11] drivers/char/ipmi: convert stats " Shuah Khan
2020-10-07 18:21 ` Kees Cook
2020-10-06 20:44 ` [PATCH v2 10/11] drivers/misc/vmw_vmci: convert num guest devices counter to counter_atomic32 Shuah Khan
2020-10-07 18:27 ` Kees Cook
2020-10-08 17:12 ` Shuah Khan
2020-10-06 20:44 ` [PATCH v2 11/11] drivers/edac: convert pci counters " Shuah Khan
2020-10-07 18:28 ` Kees Cook
2020-10-07 18:30 ` [PATCH v2 00/11] Introduce Simple atomic counters Kees Cook
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