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

Refs: #1329
Change-Id: Ia2d7641d1203f40155fef5db718d1bb2c583c1c5

test/issues/1324/C1324T03.c

@@ -0,0 +1,54 @@
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/mman.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#define GB (1024 * 1024 * 1024)
+#define MAP_SIZE (1 * GB)
+
+int main(int argc, char **argv)
+{
+	int fd = -1, ret = 0;
+	void *addr;
+	unsigned long test_val = 0x1129;
+	ssize_t val_size = sizeof(test_val);
+	unsigned long buf;
+	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;
+	}
+	memcpy(addr + offset, &test_val, val_size);
+
+	fd = open("/proc/self/mem", O_RDWR);
+	lseek(fd, (off_t)addr + offset, SEEK_SET);
+
+	read(fd, &buf, val_size);
+
+	if (buf == test_val) {
+		printf("[OK] value read by proc_mem is correct\n");
+	}
+	else {
+		ret = -1;
+		goto out;
+	}
+
+out:
+	if (fd >= 0) {
+		close(fd);
+	}
+	if (ret) {
+		printf("[NG] Test Program failed\n");
+	}
+	return ret;
+}