Fix "zygote is killed by signal 1"
Ignore the signal SIGHUP in Zygote and all its forks.
Bug:71965619
Test: manual
Change-Id: I7987bb044d97ae21ec27beca6e9aefcbe77197f5
Signed-off-by: yuanhao <yuanhao@xiaomi.com>
diff --git a/core/jni/com_android_internal_os_Zygote.cpp b/core/jni/com_android_internal_os_Zygote.cpp
index 63dba43..fa86c75 100644
--- a/core/jni/com_android_internal_os_Zygote.cpp
+++ b/core/jni/com_android_internal_os_Zygote.cpp
@@ -141,32 +141,45 @@
errno = saved_errno;
}
-// Configures the SIGCHLD handler for the zygote process. This is configured
-// very late, because earlier in the runtime we may fork() and exec()
-// other processes, and we want to waitpid() for those rather than
+// Configures the SIGCHLD/SIGHUP handlers for the zygote process. This is
+// configured very late, because earlier in the runtime we may fork() and
+// exec() other processes, and we want to waitpid() for those rather than
// have them be harvested immediately.
//
+// Ignore SIGHUP because all processes forked by the zygote are in the same
+// process group as the zygote and we don't want to be notified if we become
+// an orphaned group and have one or more stopped processes. This is not a
+// theoretical concern :
+// - we can become an orphaned group if one of our direct descendants forks
+// and is subsequently killed before its children.
+// - crash_dump routinely STOPs the process it's tracing.
+//
+// See issues b/71965619 and b/25567761 for further details.
+//
// This ends up being called repeatedly before each fork(), but there's
// no real harm in that.
-static void SetSigChldHandler() {
- struct sigaction sa;
- memset(&sa, 0, sizeof(sa));
- sa.sa_handler = SigChldHandler;
+static void SetSignalHandlers() {
+ struct sigaction sig_chld = {};
+ sig_chld.sa_handler = SigChldHandler;
- int err = sigaction(SIGCHLD, &sa, NULL);
- if (err < 0) {
+ if (sigaction(SIGCHLD, &sig_chld, NULL) < 0) {
ALOGW("Error setting SIGCHLD handler: %s", strerror(errno));
}
+
+ struct sigaction sig_hup = {};
+ sig_hup.sa_handler = SIG_IGN;
+ if (sigaction(SIGHUP, &sig_hup, NULL) < 0) {
+ ALOGW("Error setting SIGHUP handler: %s", strerror(errno));
+ }
}
// Sets the SIGCHLD handler back to default behavior in zygote children.
-static void UnsetSigChldHandler() {
+static void UnsetChldSignalHandler() {
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = SIG_DFL;
- int err = sigaction(SIGCHLD, &sa, NULL);
- if (err < 0) {
+ if (sigaction(SIGCHLD, &sa, NULL) < 0) {
ALOGW("Error unsetting SIGCHLD handler: %s", strerror(errno));
}
}
@@ -505,7 +518,7 @@
bool is_system_server, jintArray fdsToClose,
jintArray fdsToIgnore,
jstring instructionSet, jstring dataDir) {
- SetSigChldHandler();
+ SetSignalHandlers();
sigset_t sigchld;
sigemptyset(&sigchld);
@@ -682,7 +695,8 @@
delete se_info;
delete se_name;
- UnsetSigChldHandler();
+ // Unset the SIGCHLD handler, but keep ignoring SIGHUP (rationale in SetSignalHandlers).
+ UnsetChldSignalHandler();
env->CallStaticVoidMethod(gZygoteClass, gCallPostForkChildHooks, runtime_flags,
is_system_server, instructionSet);