Merge "Fix checking if process name is whitelisted"

2 files changed, 59 insertions, 3 deletions

diff --git a/services/core/java/com/android/server/am/MemoryStatUtil.java b/services/core/java/com/android/server/am/MemoryStatUtil.java
index 90fe30c7c718..a58491472036 100644
--- a/services/core/java/com/android/server/am/MemoryStatUtil.java
+++ b/services/core/java/com/android/server/am/MemoryStatUtil.java
@@ -123,9 +123,8 @@ public final class MemoryStatUtil {
      * if the file is not available.
      */
     public static String readCmdlineFromProcfs(int pid) {
-        String path = String.format(Locale.US, PROC_CMDLINE_FILE_FMT, pid);
-        String cmdline = readFileContents(path);
-        return cmdline != null ? cmdline : "";
+        final String path = String.format(Locale.US, PROC_CMDLINE_FILE_FMT, pid);
+        return parseCmdlineFromProcfs(readFileContents(path));
     }
 
     private static String readFileContents(String path) {
@@ -210,6 +209,24 @@ public final class MemoryStatUtil {
         return m.find() ? Long.parseLong(m.group(1)) * BYTES_IN_KILOBYTE : 0;
     }
 
+
+    /**
+     * Parses cmdline out of the contents of the /proc/pid/cmdline file in procfs.
+     *
+     * Parsing is required to strip anything after first null byte.
+     */
+    @VisibleForTesting
+    static String parseCmdlineFromProcfs(String cmdline) {
+        if (cmdline == null) {
+            return "";
+        }
+        int firstNullByte = cmdline.indexOf("\0");
+        if (firstNullByte == -1) {
+            return cmdline;
+        }
+        return cmdline.substring(0, firstNullByte);
+    }
+
     /**
      * Returns whether per-app memcg is available on device.
      */
diff --git a/services/tests/servicestests/src/com/android/server/am/MemoryStatUtilTest.java b/services/tests/servicestests/src/com/android/server/am/MemoryStatUtilTest.java
index 89c7b71e2cc1..93cac08f0033 100644
--- a/services/tests/servicestests/src/com/android/server/am/MemoryStatUtilTest.java
+++ b/services/tests/servicestests/src/com/android/server/am/MemoryStatUtilTest.java
@@ -20,6 +20,7 @@ import static com.android.server.am.MemoryStatUtil.BYTES_IN_KILOBYTE;
 import static com.android.server.am.MemoryStatUtil.JIFFY_NANOS;
 import static com.android.server.am.MemoryStatUtil.MemoryStat;
 import static com.android.server.am.MemoryStatUtil.PAGE_SIZE;
+import static com.android.server.am.MemoryStatUtil.parseCmdlineFromProcfs;
 import static com.android.server.am.MemoryStatUtil.parseMemoryStatFromMemcg;
 import static com.android.server.am.MemoryStatUtil.parseMemoryStatFromProcfs;
 import static com.android.server.am.MemoryStatUtil.parseVmHWMFromProcfs;
@@ -31,6 +32,7 @@ import androidx.test.filters.SmallTest;
 
 import org.junit.Test;
 
+import java.io.ByteArrayOutputStream;
 import java.util.Collections;
 
 /**
@@ -232,4 +234,41 @@ public class MemoryStatUtilTest {
 
         assertEquals(0, parseVmHWMFromProcfs(null));
     }
+
+    @Test
+    public void testParseCmdlineFromProcfs_invalidValue() {
+        byte[] nothing = new byte[] {0x00, 0x74, 0x65, 0x73, 0x74}; // \0test
+
+        assertEquals("", parseCmdlineFromProcfs(bytesToString(nothing)));
+    }
+
+    @Test
+    public void testParseCmdlineFromProcfs_correctValue_noNullBytes() {
+        assertEquals("com.google.app", parseCmdlineFromProcfs("com.google.app"));
+    }
+
+    @Test
+    public void testParseCmdlineFromProcfs_correctValue_withNullBytes() {
+        byte[] trailing = new byte[] {0x74, 0x65, 0x73, 0x74, 0x00, 0x00, 0x00}; // test\0\0\0
+
+        assertEquals("test", parseCmdlineFromProcfs(bytesToString(trailing)));
+
+        // test\0\0test
+        byte[] inside = new byte[] {0x74, 0x65, 0x73, 0x74, 0x00, 0x00, 0x74, 0x65, 0x73, 0x74};
+
+        assertEquals("test", parseCmdlineFromProcfs(bytesToString(trailing)));
+    }
+
+    @Test
+    public void testParseCmdlineFromProcfs_emptyContents() {
+        assertEquals("", parseCmdlineFromProcfs(""));
+
+        assertEquals("", parseCmdlineFromProcfs(null));
+    }
+
+    private static String bytesToString(byte[] bytes) {
+        ByteArrayOutputStream output = new ByteArrayOutputStream();
+        output.write(bytes, 0, bytes.length);
+        return output.toString();
+    }
 }