[LTP] [PATCH v2] syscalls/recvmsg03.c: add new testcase

[Xiao Yang]

On 2016/11/02 21:06, Cyril Hrubis wrote:
> Hi!
>> +static void server(void)
>> +{
>> +	int sock_fd, sock_fd2;
>> +	static char recv_buf[128];
>> +	struct sockaddr_in server_addr;
>> +	struct sockaddr_in from_addr;
>> +	struct msghdr msg;
>> +	struct iovec iov;
>> +
>> +	sock_fd2 = SAFE_SOCKET(AF_RDS, SOCK_SEQPACKET, 0);
>> +	sock_fd = sock_fd2;
>> +
>> +	memset(&server_addr, 0, sizeof(server_addr));
>> +	server_addr.sin_family = AF_INET;
>> +	server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
>> +	server_addr.sin_port = htons(4000);
>> +
>> +	SAFE_BIND(sock_fd2, (struct sockaddr *)&server_addr, sizeof(server_addr));
>> +
>> +	msg.msg_name =&from_addr;
>> +	msg.msg_namelen = sizeof(from_addr) + 16;
>> +	msg.msg_iov =&iov;
>> +	msg.msg_iovlen = 1;
>> +	msg.msg_iov->iov_base = recv_buf;
>> +	msg.msg_iov->iov_len = 128;
>> +	msg.msg_control = 0;
>> +	msg.msg_controllen = 0;
>> +	msg.msg_flags = 0;
>> +
>> +	TST_CHECKPOINT_WAKE(0);
>> +
>> +	TEST(recvmsg(sock_fd2,&msg, 0));
>> +	if (TEST_RETURN == -1) {
>> +		tst_res(TFAIL | TERRNO,
>> +		"recvmsg() failed to recvice data from client");
>> +		goto end;
>> +	}
>> +
>> +	if (msg.msg_namelen != sizeof(from_addr)) {
>> +		tst_res(TFAIL, "msg_namelen was set to %u incorrectly, "
>> +			"expected %lu", msg.msg_namelen, sizeof(from_addr));
>> +		goto end;
>> +	}
>> +
>> +	if (sock_fd2 != sock_fd) {
>> +		tst_res(TFAIL, "sock_fd was destroyed");
>> +		goto end;
>> +	}
>> +
>> +	tst_res(TPASS, "msg_namelen was set to %u correctly and sock_fd was "
>> +		"not destroyed", msg.msg_namelen);
>> +
>> +end:
>> +	SAFE_CLOSE(sock_fd2);
> I'm a bit confused here, which one of the sock_fd/sock_fd2 is destroyed?
>
> Looking at the original code in the kernel commit the sock_fd there is
> stored on the stack directly after the sockaddr_in from_addr so I guess
> that the kernel will actually write a few bytes after the end of
> from_addr structure in this case, which will rewrite the msghrd msg in
> your code. Does the test actually fail on kernel without the fix?
>
Hi Cyril

I am sorry  for the late response.  the msghrd msg was rewritten but 
sock_fd2 was not destroyed
on v3.5 kernel without the fix patch, so i will remove the code about 
checking sock_fd.

Thanks,
Xiao Yang
>> +}
>> +
>> +static void verify_recvmsg(void)
>> +{
>> +	pid_t pid;
>> +
>> +	pid = SAFE_FORK();
>> +	if (pid == 0) {
>> +		TST_CHECKPOINT_WAIT(0);
>> +		client();
>> +	} else {
>> +		server();
>> +		SAFE_WAIT(NULL);
> We should rather call tst_reap_children() in this case instead of the
> WAIT since otherwise TBROK from the client() function will not get
> propagated.
>
>> +	}
>> +}
>> +
>> +static struct tst_test test = {
>> +	.tid = "recvmsg03",
>> +	.forks_child = 1,
>> +	.needs_checkpoints = 1,
>> +	.setup = setup,
>> +	.test_all = verify_recvmsg
>> +};
>> -- 
>> 1.8.3.1
>>
>>
>>