From 66700b2c86dbef43c2b14800f84caa06eb9d2864 Mon Sep 17 00:00:00 2001
From: Dmitry Vyukov <dvyukov@google.com>
Date: Mon, 5 Dec 2016 15:50:47 +0100
Subject: executor: change the way we wait for children

waitpid(pid) does not work if child invokes ptrace(PTRACE_TRACEME):
https://groups.google.com/forum/#!topic/syzkaller/SjWzOnNRRIU
Use waitpid(-1) instead.
---
 executor/common.h    |  5 +++--
 executor/executor.cc | 14 ++++++++------
 2 files changed, 11 insertions(+), 8 deletions(-)

(limited to 'executor')

diff --git a/executor/common.h b/executor/common.h
index 19da79b5e..472db554c 100644
--- a/executor/common.h
+++ b/executor/common.h
@@ -658,7 +658,7 @@ void loop()
 		int status = 0;
 		uint64_t start = current_time_ms();
 		for (;;) {
-			int res = waitpid(pid, &status, __WALL | WNOHANG);
+			int res = waitpid(-1, &status, __WALL | WNOHANG);
 			int errno0 = errno;
 			if (res == pid)
 				break;
@@ -666,7 +666,8 @@ void loop()
 			if (current_time_ms() - start > 5 * 1000) {
 				kill(-pid, SIGKILL);
 				kill(pid, SIGKILL);
-				waitpid(pid, &status, __WALL);
+				while (waitpid(-1, &status, __WALL) != pid) {
+				}
 				break;
 			}
 		}
diff --git a/executor/executor.cc b/executor/executor.cc
index a51bd2e46..677d2919f 100644
--- a/executor/executor.cc
+++ b/executor/executor.cc
@@ -186,7 +186,7 @@ int main(int argc, char** argv)
 		fail("clone failed");
 	debug("spawned loop pid %d\n", pid);
 	int status = 0;
-	while (waitpid(pid, &status, __WALL) != pid) {
+	while (waitpid(-1, &status, __WALL) != pid) {
 	}
 	status = WEXITSTATUS(status);
 	if (status == kFailStatus)
@@ -241,7 +241,7 @@ void loop()
 		int status = 0;
 		uint64_t start = current_time_ms();
 		for (;;) {
-			int res = waitpid(pid, &status, __WALL | WNOHANG);
+			int res = waitpid(-1, &status, __WALL | WNOHANG);
 			int errno0 = errno;
 			if (res == pid) {
 				debug("waitpid(%d)=%d (%d)\n", pid, res, errno0);
@@ -253,10 +253,12 @@ void loop()
 				debug("killing\n");
 				kill(-pid, SIGKILL);
 				kill(pid, SIGKILL);
-				int res = waitpid(pid, &status, __WALL);
-				debug("waitpid(%d)=%d (%d)\n", pid, res, errno);
-				if (res != pid)
-					fail("waitpid failed");
+				for (;;) {
+					int res = waitpid(-1, &status, __WALL);
+					debug("waitpid(%d)=%d (%d)\n", pid, res, errno);
+					if (res == pid)
+						break;
+				}
 				break;
 			}
 		}
-- 
cgit mrf-deployment