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[24.9.64.241]) by smtp.gmail.com with ESMTPSA id s69sm1665627ili.54.2020.10.06.13.45.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Oct 2020 13:45:45 -0700 (PDT) From: Shuah Khan To: shuah@kernel.org, keescook@chromium.org, gregkh@linuxfoundation.org Cc: Shuah Khan , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v2 02/11] selftests:lib:test_counters: add new test for counters Date: Tue, 6 Oct 2020 14:44:33 -0600 Message-Id: X-Mailer: git-send-email 2.25.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org 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 Reviewed-by: Kees Cook --- MAINTAINERS | 1 + tools/testing/selftests/lib/Makefile | 1 + tools/testing/selftests/lib/config | 1 + tools/testing/selftests/lib/test_counters.sh | 5 +++++ 4 files changed, 8 insertions(+) create mode 100755 tools/testing/selftests/lib/test_counters.sh diff --git a/MAINTAINERS b/MAINTAINERS index 4e82d0ffcab0..26719b8dd48e 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -15845,6 +15845,7 @@ L: linux-kernel@vger.kernel.org S: Maintained F: include/linux/counters.h F: lib/test_counters.c +F: tools/testing/selftests/lib/test_counters.sh SIMPLE FIRMWARE INTERFACE (SFI) S: Obsolete diff --git a/tools/testing/selftests/lib/Makefile b/tools/testing/selftests/lib/Makefile index a105f094676e..e8960d7934e2 100644 --- a/tools/testing/selftests/lib/Makefile +++ b/tools/testing/selftests/lib/Makefile @@ -5,5 +5,6 @@ all: TEST_PROGS := printf.sh bitmap.sh prime_numbers.sh strscpy.sh +TEST_PROGS += test_counters.sh include ../lib.mk diff --git a/tools/testing/selftests/lib/config b/tools/testing/selftests/lib/config index b80ee3f6e265..6ed25024d371 100644 --- a/tools/testing/selftests/lib/config +++ b/tools/testing/selftests/lib/config @@ -3,3 +3,4 @@ CONFIG_TEST_BITMAP=m CONFIG_PRIME_NUMBERS=m CONFIG_TEST_STRSCPY=m CONFIG_TEST_BITOPS=m +CONFIG_TEST_COUNTERS=m diff --git a/tools/testing/selftests/lib/test_counters.sh b/tools/testing/selftests/lib/test_counters.sh new file mode 100755 index 000000000000..c8731aef2498 --- /dev/null +++ b/tools/testing/selftests/lib/test_counters.sh @@ -0,0 +1,5 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# Tests the Simple Atomic Counters interfaces using test_counters +# kernel module +$(dirname $0)/../kselftest/module.sh "test_counters" test_counters