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Zygote : Block SIGCHLD during fork.

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am: b1f1209d9a

Change-Id: I3658f583c82dd6243089aaa74ad731a5bfa85b01
This commit is contained in:
Narayan Kamath
2016-11-10 11:05:42 +00:00
committed by android-build-merger
parent a045aed7a2 b1f1209d9a
commit 35b8453338
1 changed files with 25 additions and 0 deletions
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25
core/jni/com_android_internal_os_Zygote.cpp
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@@ -446,6 +446,20 @@ static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArra
ckTime(start, "ForkAndSpecializeCommon:SetSigChldHandler");
sigset_t sigchld;
sigemptyset(&sigchld);
sigaddset(&sigchld, SIGCHLD);
// Temporarily block SIGCHLD during forks. The SIGCHLD handler might
// log, which would result in the logging FDs we close being reopened.
// This would cause failures because the FDs are not whitelisted.
//
// Note that the zygote process is single threaded at this point.
if (sigprocmask(SIG_BLOCK, &sigchld, NULL) == -1) {
ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno));
RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_BLOCK, { SIGCHLD }) failed.");
}
// Close any logging related FDs before we start evaluating the list of
// file descriptors.
__android_log_close();
@@ -479,6 +493,11 @@ static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArra
RuntimeAbort(env, __LINE__, "Unable to reopen whitelisted descriptors.");
}
if (sigprocmask(SIG_UNBLOCK, &sigchld, NULL) == -1) {
ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno));
RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_UNBLOCK, { SIGCHLD }) failed.");
}
// Keep capabilities across UID change, unless we're staying root.
if (uid != 0) {
EnableKeepCapabilities(env);
@@ -613,6 +632,12 @@ static pid_t ForkAndSpecializeCommon(JNIEnv* env, uid_t uid, gid_t gid, jintArra
}
} else if (pid > 0) {
// the parent process
// We blocked SIGCHLD prior to a fork, we unblock it here.
if (sigprocmask(SIG_UNBLOCK, &sigchld, NULL) == -1) {
ALOGE("sigprocmask(SIG_SETMASK, { SIGCHLD }) failed: %s", strerror(errno));
RuntimeAbort(env, __LINE__, "Call to sigprocmask(SIG_UNBLOCK, { SIGCHLD }) failed.");
}
}
return pid;
}