memtag_test: move SEGV code checks to device-side binary

Author: muhomorr

androidtest/memtag/memtag_test.cc

@@ -204,54 +204,63 @@ u8* alloc_default() {
     }
 }
 
-volatile u8 u8_var;
+int expected_segv_code;
+
+#define expect_segv(exp, segv_code) ({\
+    expected_segv_code = segv_code; \
+    volatile auto val = exp; \
+    (void) val; \
+    do_context_switch(); \
+    fprintf(stderr, "didn't receive SEGV code %i", segv_code); \
+    exit(1); })
+
+// it's expected that the device is configured to use asymm MTE tag checking mode (sync read checks,
+// async write checks)
+#define expect_read_segv(exp) expect_segv(exp, SEGV_MTESERR)
+#define expect_write_segv(exp) expect_segv(exp, SEGV_MTEAERR)
 
 void read_after_free() {
     u8 *p = alloc_default();
     free(p);
-    volatile u8 v = p[0];
-    (void) v;
+    expect_read_segv(p[0]);
 }
 
 void write_after_free() {
     u8 *p = alloc_default();
     free(p);
-    p[0] = 1;
+    expect_write_segv(p[0] = 1);
 }
 
 void underflow_read() {
     u8 *p = alloc_default();
-    volatile u8 v = p[-1];
-    (void) v;
+    expect_read_segv(p[-1]);
 }
 
 void underflow_write() {
     u8 *p = alloc_default();
-    p[-1] = 1;
+    expect_write_segv(p[-1] = 1);
 }
 
 void overflow_read() {
     u8 *p = alloc_default();
-    volatile u8 v = p[DEFAULT_ALLOC_SIZE + CANARY_SIZE];
-    (void) v;
+    expect_read_segv(p[DEFAULT_ALLOC_SIZE + CANARY_SIZE]);
 }
 
 void overflow_write() {
     u8 *p = alloc_default();
-    p[DEFAULT_ALLOC_SIZE + CANARY_SIZE] = 1;
+    expect_write_segv(p[DEFAULT_ALLOC_SIZE + CANARY_SIZE] = 1);
 }
 
 void untagged_read() {
     u8 *p = alloc_default();
     p = (u8 *) untag_pointer(p);
-    volatile u8 v = p[0];
-    (void) v;
+    expect_read_segv(p[0]);
 }
 
 void untagged_write() {
     u8 *p = alloc_default();
     p = (u8 *) untag_pointer(p);
-    p[0] = 1;
+    expect_write_segv(p[0] = 1);
 }
 
 map<string, function<void()>> tests = {
@@ -269,8 +278,12 @@ map<string, function<void()>> tests = {
 };
 
 void segv_handler(int, siginfo_t *si, void *) {
-    fprintf(stderr, "SEGV_CODE %i", si->si_code);
-    exit(139); // standard exit code for SIGSEGV
+    if (expected_segv_code == 0 || expected_segv_code != si->si_code) {
+        fprintf(stderr, "received unexpected SEGV_CODE %i", si->si_code);
+        exit(139); // standard exit code for SIGSEGV
+    }
+
+    exit(0);
 }
 
 int main(int argc, char **argv) {

androidtest/src/grapheneos/hmalloc/MemtagTest.java

@@ -7,89 +7,68 @@
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
-import java.io.IOException;
 import java.util.ArrayList;
 
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.fail;
 
 @RunWith(DeviceJUnit4ClassRunner.class)
 public class MemtagTest extends BaseHostJUnit4Test {
-
     private static final String TEST_BINARY = "/data/local/tmp/memtag_test";
 
-    enum Result {
-        SUCCESS(0, ""),
-        // it's expected that the device is configured to use asymm MTE tag checking mode
-        ASYNC_MTE_ERROR(139, "SEGV_CODE 8"),
-        SYNC_MTE_ERROR(139, "SEGV_CODE 9"),
-        ;
-
-        public final int exitCode;
-        public final String stderr;
-
-        Result(int exitCode, String stderr) {
-            this.exitCode = exitCode;
-            this.stderr = stderr;
-        }
-    }
-
-    private static final int SEGV_EXIT_CODE = 139;
-
-    private void runTest(String name, Result expectedResult) throws DeviceNotAvailableException {
+    private void runTest(String name) throws DeviceNotAvailableException {
         var args = new ArrayList<String>();
         args.add(TEST_BINARY);
         args.add(name);
         String cmdLine = String.join(" ", args);
 
         var result = getDevice().executeShellV2Command(cmdLine);
 
-        assertEquals("process exit code", expectedResult.exitCode, result.getExitCode().intValue());
-        assertEquals("stderr", expectedResult.stderr, result.getStderr());
+        assertEquals("stderr", "", result.getStderr());
+        assertEquals("process exit code", 0, result.getExitCode().intValue());
     }
 
     @Test
     public void tag_distinctness() throws DeviceNotAvailableException {
-        runTest("tag_distinctness", Result.SUCCESS);
+        runTest("tag_distinctness");
     }
 
     @Test
     public void read_after_free() throws DeviceNotAvailableException {
-        runTest("read_after_free", Result.SYNC_MTE_ERROR);
+        runTest("read_after_free");
     }
 
     @Test
     public void write_after_free() throws DeviceNotAvailableException {
-        runTest("write_after_free", Result.ASYNC_MTE_ERROR);
+        runTest("write_after_free");
     }
 
     @Test
     public void underflow_read() throws DeviceNotAvailableException {
-        runTest("underflow_read", Result.SYNC_MTE_ERROR);
+        runTest("underflow_read");
     }
 
     @Test
     public void underflow_write() throws DeviceNotAvailableException {
-        runTest("underflow_write", Result.ASYNC_MTE_ERROR);
+        runTest("underflow_write");
     }
 
     @Test
     public void overflow_read() throws DeviceNotAvailableException {
-        runTest("overflow_read", Result.SYNC_MTE_ERROR);
+        runTest("overflow_read");
     }
 
     @Test
     public void overflow_write() throws DeviceNotAvailableException {
-        runTest("overflow_write", Result.ASYNC_MTE_ERROR);
+        runTest("overflow_write");
     }
 
     @Test
     public void untagged_read() throws DeviceNotAvailableException {
-        runTest("untagged_read", Result.SYNC_MTE_ERROR);
+        runTest("untagged_read");
     }
 
     @Test
     public void untagged_write() throws DeviceNotAvailableException {
-        runTest("untagged_write", Result.ASYNC_MTE_ERROR);
+        runTest("untagged_write");
     }
 }