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Commit 9dc56ace authored by Rafal Slawik's avatar Rafal Slawik
Browse files

Fix checking if process name is whitelisted 

Process name (its command line) returned from procfs contains null bytes
and the check if the name is in the whitelist always failed.
Trim process name before comparing.

Test: atest UidAtomTests#testProcessMemoryState
Change-Id: I4e307b7c14d5962aea9fc86a53764f9cc0ebd1b8
Fixes: 120782694
parent 407396e3

services/core/java/com/android/server/am/MemoryStatUtil.java

+20 −3
Original line number Diff line number Diff line
@@ -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.

     */

services/tests/servicestests/src/com/android/server/am/MemoryStatUtilTest.java

+39 −0
Original line number Diff line number Diff line
@@ -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();

    }

}