[PATCH 5.4 2/2] nvmet-tcp: Fix a possible UAF in queue intialization setup

[Dragos-Marian Panait <dragos.panait@windriver.com>]

From: Sagi Grimberg <sagi@grimberg.me>

commit d920abd1e7c4884f9ecd0749d1921b7ab19ddfbd upstream.

From Alon:
"Due to a logical bug in the NVMe-oF/TCP subsystem in the Linux kernel,
a malicious user can cause a UAF and a double free, which may lead to
RCE (may also lead to an LPE in case the attacker already has local
privileges)."

Hence, when a queue initialization fails after the ahash requests are
allocated, it is guaranteed that the queue removal async work will be
called, hence leave the deallocation to the queue removal.

Also, be extra careful not to continue processing the socket, so set
queue rcv_state to NVMET_TCP_RECV_ERR upon a socket error.

Cc: stable@vger.kernel.org
Reported-by: Alon Zahavi <zahavi.alon@gmail.com>
Tested-by: Alon Zahavi <zahavi.alon@gmail.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Dragos-Marian Panait <dragos.panait@windriver.com>
---
 drivers/nvme/target/tcp.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index e63a50e22e5a..e8c7135c4c11 100644
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -323,6 +323,7 @@ static void nvmet_tcp_fatal_error(struct nvmet_tcp_queue *queue)
 
 static void nvmet_tcp_socket_error(struct nvmet_tcp_queue *queue, int status)
 {
+	queue->rcv_state = NVMET_TCP_RECV_ERR;
 	if (status == -EPIPE || status == -ECONNRESET)
 		kernel_sock_shutdown(queue->sock, SHUT_RDWR);
 	else
@@ -828,15 +829,11 @@ static int nvmet_tcp_handle_icreq(struct nvmet_tcp_queue *queue)
 	iov.iov_len = sizeof(*icresp);
 	ret = kernel_sendmsg(queue->sock, &msg, &iov, 1, iov.iov_len);
 	if (ret < 0)
-		goto free_crypto;
+		return ret; /* queue removal will cleanup */
 
 	queue->state = NVMET_TCP_Q_LIVE;
 	nvmet_prepare_receive_pdu(queue);
 	return 0;
-free_crypto:
-	if (queue->hdr_digest || queue->data_digest)
-		nvmet_tcp_free_crypto(queue);
-	return ret;
 }
 
 static void nvmet_tcp_handle_req_failure(struct nvmet_tcp_queue *queue,
-- 
2.42.0