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AJvYcCX3rVY2Eav0gdLPN3uds0yinAGkqjzS55nsUAndDT27CzGEDGsEgHV9gsvSkxvkIccFOAO0h9Ge6zi6dd8=@vger.kernel.org X-Gm-Message-State: AOJu0YwOQMNhzF4JJ0hiaHlpXOmlVgH4HdN0U9+/hER3V84+w1FNos8t /fLRIvuBgLw3t+Up3TuJxPQFN/NaoO7eeyKQ/qk0W8schZFGDaf/ X-Google-Smtp-Source: AGHT+IEh+03XEiMqqry8FUshMBqgkfrf1RSIoqUMOizfeEEK1dQF3s6/BBgO7zm3R3vKt4nsjoIx9w== X-Received: by 2002:a17:90a:7c0b:b0:2e2:d562:6b42 with SMTP id 98e67ed59e1d1-2e2f0a2ab4fmr5981947a91.3.1728918362003; Mon, 14 Oct 2024 08:06:02 -0700 (PDT) Received: from [192.168.1.17] ([171.76.87.218]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2e2e922a8dcsm3538236a91.0.2024.10.14.08.05.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 14 Oct 2024 08:06:01 -0700 (PDT) Message-ID: Date: Mon, 14 Oct 2024 20:35:56 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] kasan: add kunit tests for kmalloc_track_caller, kmalloc_node_track_caller To: Andrey Konovalov Cc: ryabinin.a.a@gmail.com, dvyukov@google.com, skhan@linuxfoundation.org, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org References: <20241014041130.1768674-1-niharchaithanya@gmail.com> Content-Language: en-US From: Nihar Chaithanya In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 14/10/24 18:19, Andrey Konovalov wrote: > On Mon, Oct 14, 2024 at 6:32 AM Nihar Chaithanya > wrote: >> The Kunit tests for kmalloc_track_caller and kmalloc_node_track_caller >> were missing in kasan_test_c.c, which check that these functions poison >> the memory properly. >> >> Add a Kunit test: >> -> kmalloc_tracker_caller_oob_right(): This includes out-of-bounds >> access test for kmalloc_track_caller and kmalloc_node_track_caller. >> >> Signed-off-by: Nihar Chaithanya >> Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=216509 >> --- >> v1->v2: Simplified the three separate out-of-bounds tests to a single test for >> kmalloc_track_caller. >> >> Link to v1: https://lore.kernel.org/all/20241013172912.1047136-1-niharchaithanya@gmail.com/ >> >> mm/kasan/kasan_test_c.c | 32 ++++++++++++++++++++++++++++++++ >> 1 file changed, 32 insertions(+) >> >> diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c >> index a181e4780d9d..62efc1ee9612 100644 >> --- a/mm/kasan/kasan_test_c.c >> +++ b/mm/kasan/kasan_test_c.c >> @@ -213,6 +213,37 @@ static void kmalloc_node_oob_right(struct kunit *test) >> kfree(ptr); >> } >> >> +static void kmalloc_track_caller_oob_right(struct kunit *test) >> +{ >> + char *ptr; >> + size_t size = 128 - KASAN_GRANULE_SIZE; >> + >> + /* >> + * Check that KASAN detects out-of-bounds access for object allocated via >> + * kmalloc_track_caller(). >> + */ >> + ptr = kmalloc_track_caller(size, GFP_KERNEL); >> + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); >> + >> + OPTIMIZER_HIDE_VAR(ptr); >> + KUNIT_EXPECT_KASAN_FAIL(test, ptr[size] = 'y'); >> + >> + kfree(ptr); >> + >> + /* >> + * Check that KASAN detects out-of-bounds access for object allocated via >> + * kmalloc_node_track_caller(). >> + */ >> + size = 4096; >> + ptr = kmalloc_node_track_caller(size, GFP_KERNEL, 0); >> + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); >> + >> + OPTIMIZER_HIDE_VAR(ptr); >> + KUNIT_EXPECT_KASAN_FAIL(test, ptr[size] = 'y'); > What you had here before (ptr[0] = ptr[size]) was better. ptr[size] = > 'y' with size == 4096 does an out-of-bounds write access, which > corrupts uncontrolled memory for the tag-based KASAN modes, which do > not use redzones. We try to avoid corrupting memory in KASAN tests, as > the kernel might crash otherwise before all tests complete. > > So let's either change this back to ptr[0] = ptr[size] or just reuse > the same size for both test cases (or does kmalloc_node_track_caller > require size >= 4K?). We can reuse the same test for both cases without changing the size, I ran the test without changing the size (i.e., size == 128 - KASAN_GRANULE_SIZE), the KASAN report was generated. I found instances (drm/tiny) where the size passed to the kmalloc_node_track_caller is < 4k. >> + >> + kfree(ptr); >> +} >> + >> /* >> * Check that KASAN detects an out-of-bounds access for a big object allocated >> * via kmalloc(). But not as big as to trigger the page_alloc fallback. >> @@ -1958,6 +1989,7 @@ static struct kunit_case kasan_kunit_test_cases[] = { >> KUNIT_CASE(kmalloc_oob_right), >> KUNIT_CASE(kmalloc_oob_left), >> KUNIT_CASE(kmalloc_node_oob_right), >> + KUNIT_CASE(kmalloc_track_caller_oob_right), >> KUNIT_CASE(kmalloc_big_oob_right), >> KUNIT_CASE(kmalloc_large_oob_right), >> KUNIT_CASE(kmalloc_large_uaf), >> -- >> 2.34.1 >>