linux-kernel - [PATCH] nvme-tcp: Fix use-after-free of netns by kernel TCP socket.

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Message-ID: <20250408224105.2344-1-kuniyu@amazon.com>
Date: Tue, 8 Apr 2025 15:40:54 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: Keith Busch <kbusch@...nel.org>, Jens Axboe <axboe@...nel.dk>, "Christoph
 Hellwig" <hch@....de>, Sagi Grimberg <sagi@...mberg.me>
CC: Peijie Shao <shaopeijie@...tc.cn>, Kuniyuki Iwashima <kuniyu@...zon.com>,
	Kuniyuki Iwashima <kuni1840@...il.com>, <linux-nvme@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH] nvme-tcp: Fix use-after-free of netns by kernel TCP socket.

Commit 1be52169c348 ("nvme-tcp: fix selinux denied when calling
sock_sendmsg") converted sock_create() in nvme_tcp_alloc_queue()
to sock_create_kern().

sock_create_kern() creates a kernel socket, which does not hold
a reference to netns.  If the code does not manage the netns
lifetime properly, use-after-free could happen.

Also, TCP kernel socket with sk_net_refcnt 0 has a socket leak
problem: it remains FIN_WAIT_1 if it misses FIN after close()
because tcp_close() stops all timers.

To fix such problems, let's hold netns ref by sk_net_refcnt_upgrade().

We had the same issue in CIFS, SMC, etc, and applied the same
solution, see commit ef7134c7fc48 ("smb: client: Fix use-after-free
of network namespace.") and commit 9744d2bf1976 ("smc: Fix
use-after-free in tcp_write_timer_handler().").

Fixes: 1be52169c348 ("nvme-tcp: fix selinux denied when calling sock_sendmsg")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
 drivers/nvme/host/tcp.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 26c459f0198d..72d260201d8c 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -1803,6 +1803,8 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl, int qid,
 		ret = PTR_ERR(sock_file);
 		goto err_destroy_mutex;
 	}
+
+	sk_net_refcnt_upgrade(queue->sock->sk);
 	nvme_tcp_reclassify_socket(queue->sock);

 	/* Single syn retry */
-- 
2.49.0