From 00c0cd4a24bd0f040055f9e786e2df1fa3b7d2d3 Mon Sep 17 00:00:00 2001
From: Jeff Brown <jeffbrown@google.com>
Date: Wed, 10 Sep 2014 16:48:46 -0700
Subject: [PATCH] Clean entire arg block when setting process name.

When Android processes fork from Zygote, we rewrite the command line
with a new name, eg. "system_server".  When we do this, we should
fill the entire block with zeros to remove corrupted argument
information that may otherwise remain in the /proc/<pid>/cmdline buffer
and be seen in tools and stack dumps.

Fixed an issue where VM options could be overwritten after setting
the nice name if the name was too long.

Bug: 17474152
Change-Id: Ie6cf9ed7752a04300a340e26cd6812bb35c59e1b
---
 cmds/app_process/app_main.cpp            | 29 ++++++++++++++++++++---------
 core/jni/AndroidRuntime.cpp              | 23 +----------------------
 include/android_runtime/AndroidRuntime.h |  4 +---
 3 files changed, 22 insertions(+), 34 deletions(-)

diff --git a/cmds/app_process/app_main.cpp b/cmds/app_process/app_main.cpp
index 6e77e1324e03..1bb28c38ceef 100644
--- a/cmds/app_process/app_main.cpp
+++ b/cmds/app_process/app_main.cpp
@@ -133,8 +133,7 @@ static size_t computeArgBlockSize(int argc, char* const argv[]) {
     // names if the zygote command line decreases in size.
     uintptr_t start = reinterpret_cast<uintptr_t>(argv[0]);
     uintptr_t end = reinterpret_cast<uintptr_t>(argv[argc - 1]);
-    end += strlen(argv[argc - 1]);
-
+    end += strlen(argv[argc - 1]) + 1;
     return (end - start);
 }
 
@@ -220,15 +219,27 @@ int main(int argc, char* const argv[])
     //
     // For zygote starts, all remaining arguments are passed to the zygote.
     // main function.
+    //
+    // Note that we must copy argument string values since we will rewrite the
+    // entire argument block when we apply the nice name to argv0.
 
-
-    int i = runtime.addVmArguments(argc, argv);
+    int i;
+    for (i = 0; i < argc; i++) {
+        if (argv[i][0] != '-') {
+            break;
+        }
+        if (argv[i][1] == '-' && argv[i][2] == 0) {
+            ++i; // Skip --.
+            break;
+        }
+        runtime.addOption(strdup(argv[i]));
+    }
 
     // Parse runtime arguments.  Stop at first unrecognized option.
     bool zygote = false;
     bool startSystemServer = false;
     bool application = false;
-    const char* niceName = NULL;
+    String8 niceName;
     String8 className;
 
     ++i;  // Skip unused "parent dir" argument.
@@ -242,7 +253,7 @@ int main(int argc, char* const argv[])
         } else if (strcmp(arg, "--application") == 0) {
             application = true;
         } else if (strncmp(arg, "--nice-name=", 12) == 0) {
-            niceName = arg + 12;
+            niceName.setTo(arg + 12);
         } else if (strncmp(arg, "--", 2) != 0) {
             className.setTo(arg);
             break;
@@ -287,9 +298,9 @@ int main(int argc, char* const argv[])
         }
     }
 
-    if (niceName && *niceName) {
-        runtime.setArgv0(niceName);
-        set_process_name(niceName);
+    if (!niceName.isEmpty()) {
+        runtime.setArgv0(niceName.string());
+        set_process_name(niceName.string());
     }
 
     if (zygote) {
diff --git a/core/jni/AndroidRuntime.cpp b/core/jni/AndroidRuntime.cpp
index a63258c8e657..157310657c59 100644
--- a/core/jni/AndroidRuntime.cpp
+++ b/core/jni/AndroidRuntime.cpp
@@ -271,6 +271,7 @@ AndroidRuntime::~AndroidRuntime()
 }
 
 void AndroidRuntime::setArgv0(const char* argv0) {
+    memset(mArgBlockStart, 0, mArgBlockLength);
     strlcpy(mArgBlockStart, argv0, mArgBlockLength);
 }
 
@@ -345,28 +346,6 @@ static bool runtime_isSensitiveThread() {
     return state && state->getStrictModePolicy() != 0;
 }
 
-
-/**
- * Add VM arguments to the to-be-executed VM
- * Stops at first non '-' argument (also stops at an argument of '--')
- * Returns the number of args consumed
- */
-int AndroidRuntime::addVmArguments(int argc, const char* const argv[])
-{
-    int i;
-
-    for (i = 0; i<argc; i++) {
-        if (argv[i][0] != '-') {
-            return i;
-        }
-        if (argv[i][1] == '-' && argv[i][2] == 0) {
-            return i+1;
-        }
-        addOption(argv[i]);
-    }
-    return i;
-}
-
 static int hasDir(const char* dir)
 {
     struct stat s;
diff --git a/include/android_runtime/AndroidRuntime.h b/include/android_runtime/AndroidRuntime.h
index 51e47e6e24d8..f3cfd97d58ee 100644
--- a/include/android_runtime/AndroidRuntime.h
+++ b/include/android_runtime/AndroidRuntime.h
@@ -45,6 +45,7 @@ public:
     };
 
     void setArgv0(const char* argv0);
+    void addOption(const char* optionString, void* extra_info = NULL);
 
     /**
      * Register a set of methods in the specified class.
@@ -63,8 +64,6 @@ public:
      */
     static jclass findClass(JNIEnv* env, const char* className);
 
-    int addVmArguments(int argc, const char* const argv[]);
-
     void start(const char *classname, const Vector<String8>& options);
 
     void exit(int code);
@@ -116,7 +115,6 @@ public:
 
 private:
     static int startReg(JNIEnv* env);
-    void addOption(const char* optionString, void* extra_info = NULL);
     bool parseRuntimeOption(const char* property,
                             char* buffer,
                             const char* runtimeArg,
-- 
2.11.0