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Fix cancellation race problem for aysnc DNS API

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This problem might cause double-close fd and result in app crash
or unexpected behaviour

Bug: 129317069
Test: atest DnsResolverTest
      manual test with delaying response callback/cancel
Change-Id: I223234f527edafc51d34fa6be390419c05def8d8
This commit is contained in:
Luke Huang
2019-03-26 15:50:10 +08:00
parent 5c83418408
commit e17bb2dff4
2 changed files with 37 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
core/java/android/net/DnsResolver.java
View File

@@ -205,6 +205,7 @@ public final class DnsResolver {
if (cancellationSignal != null && cancellationSignal.isCanceled()) {
return;
}
final Object lock = new Object();
final FileDescriptor queryfd;
try {
queryfd = resNetworkSend((network != null
@@ -214,8 +215,8 @@ public final class DnsResolver {
return;
}
maybeAddCancellationSignal(cancellationSignal, queryfd);
registerFDListener(executor, queryfd, callback);
maybeAddCancellationSignal(cancellationSignal, queryfd, lock);
registerFDListener(executor, queryfd, callback, cancellationSignal, lock);
}
/**
@@ -242,6 +243,7 @@ public final class DnsResolver {
if (cancellationSignal != null && cancellationSignal.isCanceled()) {
return;
}
final Object lock = new Object();
final FileDescriptor queryfd;
try {
queryfd = resNetworkQuery((network != null
@@ -251,17 +253,22 @@ public final class DnsResolver {
return;
}
maybeAddCancellationSignal(cancellationSignal, queryfd);
registerFDListener(executor, queryfd, callback);
maybeAddCancellationSignal(cancellationSignal, queryfd, lock);
registerFDListener(executor, queryfd, callback, cancellationSignal, lock);
}
private <T> void registerFDListener(@NonNull Executor executor,
@NonNull FileDescriptor queryfd, @NonNull AnswerCallback<T> answerCallback) {
@NonNull FileDescriptor queryfd, @NonNull AnswerCallback<T> answerCallback,
@Nullable CancellationSignal cancellationSignal, @NonNull Object lock) {
Looper.getMainLooper().getQueue().addOnFileDescriptorEventListener(
queryfd,
FD_EVENTS,
(fd, events) -> {
executor.execute(() -> {
synchronized (lock) {
if (cancellationSignal != null && cancellationSignal.isCanceled()) {
return;
}
byte[] answerbuf = null;
try {
answerbuf = resNetworkResult(fd);
@@ -277,6 +284,7 @@ public final class DnsResolver {
} catch (ParseException e) {
answerCallback.onParseException(e);
}
}
});
// Unregister this fd listener
return 0;
@@ -284,13 +292,15 @@ public final class DnsResolver {
}
private void maybeAddCancellationSignal(@Nullable CancellationSignal cancellationSignal,
@NonNull FileDescriptor queryfd) {
@NonNull FileDescriptor queryfd, @NonNull Object lock) {
if (cancellationSignal == null) return;
cancellationSignal.setOnCancelListener(
() -> {
cancellationSignal.setOnCancelListener(() -> {
synchronized (lock) {
if (!queryfd.valid()) return;
Looper.getMainLooper().getQueue()
.removeOnFileDescriptorEventListener(queryfd);
resNetworkCancel(queryfd);
}
});
}

2
core/jni/android_net_NetUtils.cpp
View File

@@ -470,6 +470,7 @@ static jbyteArray android_net_utils_resNetworkResult(JNIEnv *env, jobject thiz,
std::vector<uint8_t> buf(MAXPACKETSIZE, 0);
int res = resNetworkResult(fd, &rcode, buf.data(), MAXPACKETSIZE);
jniSetFileDescriptorOfFD(env, javaFd, -1);
if (res < 0) {
throwErrnoException(env, "resNetworkResult", -res);
return nullptr;
@@ -490,6 +491,7 @@ static jbyteArray android_net_utils_resNetworkResult(JNIEnv *env, jobject thiz,
static void android_net_utils_resNetworkCancel(JNIEnv *env, jobject thiz, jobject javaFd) {
int fd = jniGetFDFromFileDescriptor(env, javaFd);
resNetworkCancel(fd);
jniSetFileDescriptorOfFD(env, javaFd, -1);
}
static jobject android_net_utils_getTcpRepairWindow(JNIEnv *env, jobject thiz, jobject javaFd) {