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[87.12.139.105]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4887ad477f6sm38285485e9.7.2026.04.01.02.21.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Apr 2026 02:21:55 -0700 (PDT) From: Stefano Garzarella To: netdev@vger.kernel.org Cc: Stefano Garzarella , "David S. Miller" , linux-kernel@vger.kernel.org, Bobby Eshleman , Jakub Kicinski , Simon Horman , virtualization@lists.linux.dev, Eric Dumazet , Paolo Abeni , Jin Liu Subject: [PATCH net] vsock: initialize child_ns_mode_locked in vsock_net_init() Date: Wed, 1 Apr 2026 11:21:53 +0200 Message-ID: <20260401092153.28462-1-sgarzare@redhat.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Stefano Garzarella The `child_ns_mode_locked` field lives in `struct net`, which persists across vsock module reloads. When the module is unloaded and reloaded, `vsock_net_init()` resets `mode` and `child_ns_mode` back to their default values, but does not reset `child_ns_mode_locked`. The stale lock from the previous module load causes subsequent writes to `child_ns_mode` to silently fail: `vsock_net_set_child_mode()` sees the old lock, skips updating the actual value, and returns success when the requested mode matches the stale lock. The sysctl handler reports no error, but `child_ns_mode` remains unchanged. Steps to reproduce: $ modprobe vsock $ echo local > /proc/sys/net/vsock/child_ns_mode $ cat /proc/sys/net/vsock/child_ns_mode local $ modprobe -r vsock $ modprobe vsock $ echo local > /proc/sys/net/vsock/child_ns_mode $ cat /proc/sys/net/vsock/child_ns_mode global <--- expected "local" Fix this by initializing `child_ns_mode_locked` to 0 (unlocked) in `vsock_net_init()`, so the write-once mechanism works correctly after module reload. Fixes: 102eab95f025 ("vsock: lock down child_ns_mode as write-once") Cc: bobbyeshleman@meta.com Reported-by: Jin Liu Signed-off-by: Stefano Garzarella --- net/vmw_vsock/af_vsock.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index 2f7d94d682cb..d912ed2f012a 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -2928,6 +2928,7 @@ static void vsock_net_init(struct net *net) net->vsock.mode = vsock_net_child_mode(current->nsproxy->net_ns); net->vsock.child_ns_mode = net->vsock.mode; + net->vsock.child_ns_mode_locked = 0; } static __net_init int vsock_sysctl_init_net(struct net *net) -- 2.53.0