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Commit 6c93d632 authored by Chris Wailes's avatar Chris Wailes
Browse files

Reset stack guard after fork from Zygote 

Bug: 168258494
Test: Check log for change in stack guard
Change-Id: I8a2671b54497faaba0c368df9f755e6e9197f267
parent 1f02cb71

core/jni/com_android_internal_os_Zygote.cpp

+15 −0
Original line number Diff line number Diff line
@@ -94,6 +94,10 @@ 


#include "nativebridge/native_bridge.h"



#if defined(__BIONIC__)

extern "C" void android_reset_stack_guards();

#endif



namespace {



// TODO (chriswailes): Add a function to initialize native Zygote data.
@@ -412,6 +416,7 @@ static void sendSigChildStatus(const pid_t pid, const uid_t uid, const int statu 
}



// This signal handler is for zygote mode, since the zygote must reap its children

NO_STACK_PROTECTOR

static void SigChldHandler(int /*signal_number*/, siginfo_t* info, void* /*ucontext*/) {

    pid_t pid;

    int status;
@@ -2042,6 +2047,7 @@ static std::set<int>* gPreloadFds = nullptr; 
static bool gPreloadFdsExtracted = false;



// Utility routine to fork a process from the zygote.

NO_STACK_PROTECTOR

pid_t zygote::ForkCommon(JNIEnv* env, bool is_system_server,

                         const std::vector<int>& fds_to_close,

                         const std::vector<int>& fds_to_ignore,
@@ -2098,6 +2104,11 @@ pid_t zygote::ForkCommon(JNIEnv* env, bool is_system_server, 
      setpriority(PRIO_PROCESS, 0, PROCESS_PRIORITY_MIN);

    }



#if defined(__BIONIC__)

    // Reset the stack guard for the new process.

    android_reset_stack_guards();

#endif



    // The child process.

    PreApplicationInit();
@@ -2130,6 +2141,7 @@ static void com_android_internal_os_Zygote_nativePreApplicationInit(JNIEnv*, jcl 
  PreApplicationInit();

}



NO_STACK_PROTECTOR

static jint com_android_internal_os_Zygote_nativeForkAndSpecialize(

        JNIEnv* env, jclass, jint uid, jint gid, jintArray gids, jint runtime_flags,

        jobjectArray rlimits, jint mount_external, jstring se_info, jstring nice_name,
@@ -2184,6 +2196,7 @@ static jint com_android_internal_os_Zygote_nativeForkAndSpecialize( 
    return pid;

}



NO_STACK_PROTECTOR

static jint com_android_internal_os_Zygote_nativeForkSystemServer(

        JNIEnv* env, jclass, uid_t uid, gid_t gid, jintArray gids,

        jint runtime_flags, jobjectArray rlimits, jlong permitted_capabilities,
@@ -2255,6 +2268,7 @@ static jint com_android_internal_os_Zygote_nativeForkSystemServer( 
 * @param is_priority_fork  Controls the nice level assigned to the newly created process

 * @return child pid in the parent, 0 in the child

 */

NO_STACK_PROTECTOR

static jint com_android_internal_os_Zygote_nativeForkApp(JNIEnv* env,

                                                         jclass,

                                                         jint read_pipe_fd,
@@ -2269,6 +2283,7 @@ static jint com_android_internal_os_Zygote_nativeForkApp(JNIEnv* env, 
                            args_known == JNI_TRUE, is_priority_fork == JNI_TRUE, true);

}



NO_STACK_PROTECTOR

int zygote::forkApp(JNIEnv* env,

                    int read_pipe_fd,

                    int write_pipe_fd,

core/jni/com_android_internal_os_Zygote.h

+8 −0
Original line number Diff line number Diff line
@@ -20,6 +20,14 @@ 
#define LOG_TAG "Zygote"

#define ATRACE_TAG ATRACE_TAG_DALVIK



/*

 * All functions that lead to ForkCommon must be marked with the

 * no_stack_protector attributed.  Because ForkCommon changes the stack

 * protector cookie, all of the guard checks on the frames above ForkCommon

 * would fail when they are popped.

 */

#define NO_STACK_PROTECTOR __attribute__((no_stack_protector))



#include <jni.h>

#include <vector>

#include <android-base/stringprintf.h>

core/jni/com_android_internal_os_ZygoteCommandBuffer.cpp

+1 −0
Original line number Diff line number Diff line
@@ -377,6 +377,7 @@ void com_android_internal_os_ZygoteCommandBuffer_nativeReadFullyAndReset(JNIEnv* 
// We only process fork commands if the peer uid matches expected_uid.

// For every fork command after the first, we check that the requested uid is at

// least minUid.

NO_STACK_PROTECTOR

jboolean com_android_internal_os_ZygoteCommandBuffer_nativeForkRepeatedly(

            JNIEnv* env,

            jclass,