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Rao" , linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Jinchao Wang Subject: [PATCH 13/17] mm/ksw: add stack overflow test Date: Thu, 28 Aug 2025 15:32:46 +0800 Message-ID: <20250828073311.1116593-14-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250828073311.1116593-1-wangjinchao600@gmail.com> References: <20250828073311.1116593-1-wangjinchao600@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Extend the test module with a new test case (test1) that intentionally overflows a local u64 buffer to corrupt the stack canary. This helps validate KStackWatch's detection of stack corruption under overflow conditions. The proc interface is updated to document the new test: - test1: stack canary overflow test Signed-off-by: Jinchao Wang --- mm/kstackwatch/kstackwatch_test.c | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) diff --git a/mm/kstackwatch/kstackwatch_test.c b/mm/kstackwatch/kstackwatch= _test.c index bba2ab8530ed..138163472b03 100644 --- a/mm/kstackwatch/kstackwatch_test.c +++ b/mm/kstackwatch/kstackwatch_test.c @@ -42,6 +42,27 @@ static void canary_test_write(void) pr_info("KSW: test: canary write test completed\n"); } =20 +/* + * Test Case 1: Stack Overflow (Canary Test) + * This function uses a u64 buffer 64-bit write + * to corrupt the stack canary with a single operation + */ +static void canary_test_overflow(void) +{ + u64 buffer[BUFFER_SIZE]; + + pr_info("KSW: test: starting %s with u64 write\n", __func__); + pr_info("KSW: test: buffer 0x%px\n", buffer); + + /* intentionally overflow the u64 buffer. */ + buffer[BUFFER_SIZE] =3D 0xdeadbeefdeadbeef; + + /* make sure the compiler do not drop assign action */ + barrier_data(buffer); + + pr_info("KSW: test: canary overflow test completed\n"); +} + static ssize_t test_proc_write(struct file *file, const char __user *buffe= r, size_t count, loff_t *pos) { @@ -65,7 +86,10 @@ static ssize_t test_proc_write(struct file *file, const = char __user *buffer, pr_info("KSW: test: triggering canary write test\n"); canary_test_write(); break; - + case 1: + pr_info("KSW: test: triggering canary overflow test\n"); + canary_test_overflow(); + break; default: pr_err("KSW: test: Unknown test number %d\n", test_num); return -EINVAL; @@ -85,7 +109,8 @@ static ssize_t test_proc_read(struct file *file, char __= user *buffer, "KStackWatch Simplified Test Module\n" "=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D\n" "Usage:\n" - " echo 'test0' > /proc/kstackwatch_test - canary write test\n"; + " echo 'test0' > /proc/kstackwatch_test - Canary write test\n" + " echo 'test1' > /proc/kstackwatch_test - Canary overflow test\n"; =20 return simple_read_from_buffer(buffer, count, pos, usage, strlen(usage)); --=20 2.43.0