[PATCH v4] nvme-tcp: fix connect failure on receiving partial ICResp PDU

[Caleb Sander Mateos <csander@purestorage.com>]

nvme_tcp_init_connection() attempts to receive an ICResp PDU but only
checks that the return value from recvmsg() is non-negative. If the
sender closes the TCP connection or sends fewer than 128 bytes, this
check will pass even though the full PDU wasn't received.

Ensure the full ICResp PDU is received by checking that recvmsg()
returns the expected 128 bytes.

Additionally set the MSG_WAITALL flag for recvmsg(), as a sender could
split the ICResp over multiple TCP frames. Without MSG_WAITALL,
recvmsg() could return prematurely with only part of the PDU.

Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: 3f2304f8c6d6 ("nvme-tcp: add NVMe over TCP host driver")
---
v4: keep recvmsg() error return value
v3: fix return value to indicate error
v2: add Fixes tag

 drivers/nvme/host/tcp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index e9ff6babc540..56679eb8c0d6 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -1446,15 +1446,18 @@ static int nvme_tcp_init_connection(struct nvme_tcp_queue *queue)
 	iov.iov_len = sizeof(*icresp);
 	if (nvme_tcp_queue_tls(queue)) {
 		msg.msg_control = cbuf;
 		msg.msg_controllen = sizeof(cbuf);
 	}
+	msg.msg_flags = MSG_WAITALL;
 	ret = kernel_recvmsg(queue->sock, &msg, &iov, 1,
 			iov.iov_len, msg.msg_flags);
-	if (ret < 0) {
+	if (ret < sizeof(*icresp)) {
 		pr_warn("queue %d: failed to receive icresp, error %d\n",
 			nvme_tcp_queue_id(queue), ret);
+		if (ret >= 0)
+			ret = -ECONNRESET;
 		goto free_icresp;
 	}
 	ret = -ENOTCONN;
 	if (nvme_tcp_queue_tls(queue)) {
 		ctype = tls_get_record_type(queue->sock->sk,
-- 
2.45.2