fix: fork's race-condition caused by child and grand-child

Refs: #1329
Change-Id: Ia2d7641d1203f40155fef5db718d1bb2c583c1c5

test/issues/1324/C1324T01.c

@@ -0,0 +1,100 @@
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/mman.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/ptrace.h>
+#include <signal.h>
+
+
+#define GB (1024 * 1024 * 1024)
+#define MAP_SIZE (1 * GB)
+
+int main(int argc, char **argv)
+{
+	int rc, ret = 0;
+	int pid, status;
+	void *addr;
+	unsigned long test_val = 0x1129;
+	ssize_t val_size = sizeof(test_val);
+	ssize_t offset = MAP_SIZE - val_size;
+
+	addr = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	if (addr == MAP_FAILED) {
+		ret = -1;
+		perror("failed to mmap: ");
+		goto out;
+	}
+	memset(addr, '0', MAP_SIZE);
+
+	pid = fork();
+	if (pid < 0) {
+		ret = -1;
+		perror("failed to fork: ");
+		goto out;
+	}
+
+	if (pid == 0) {
+		/* child */
+		printf("[OK] fork is successful\n");
+
+		rc = ptrace(PTRACE_TRACEME, 0, NULL, NULL);
+		if (rc < 0) {
+			printf("[NG]: traceme is failed\n");
+		}
+		raise(SIGSTOP);
+
+		if (*((unsigned long *)(addr + offset)) == test_val) {
+			printf("[OK] POKED value is correct!!\n");
+		}
+		else {
+			printf("[NG] POKED value is NOT correct!!\n");
+			exit(-1);
+		}
+
+		exit(0);
+	}
+	else {
+		waitpid(pid, &status, 0);
+		if (!WIFSTOPPED(status)) {
+			ret = -1;
+			goto out;
+		}
+
+		rc = ptrace(PTRACE_POKETEXT, pid, addr + offset, test_val);
+		if (rc < 0) {
+			ret = -1;
+			goto out;
+		}
+
+		rc = ptrace(PTRACE_DETACH, pid, NULL, NULL);
+		if (rc < 0) {
+			ret = -1;
+			goto out;
+		}
+
+		waitpid(pid, &status, 0);
+		if (WIFEXITED(status)) {
+			if (WEXITSTATUS(status) == 0) {
+				printf("[OK] child exited normaly\n");
+			}
+			else {
+				ret = -1;
+				goto out;
+			}
+		}
+		else {
+			ret = -1;
+			goto out;
+		}
+	}
+
+out:
+	if (ret) {
+		printf("[NG] Test Program failed\n");
+	}
+	return ret;
+}