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([187.13.206.89]) by smtp.gmail.com with ESMTPSA id ada2fe7eead31-79fb104b2a6sm310677137.3.2026.09.15.10.31.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Sep 2026 10:31:05 -0700 (PDT) From: Aldo Ariel Panzardo To: Stefano Garzarella Cc: Bobby Eshleman , Luigi Leonardi , davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, virtualization@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Aldo Ariel Panzardo Subject: [PATCH v3] vsock: ignore empty child namespace mode writes Date: Tue, 15 Sep 2026 14:30:50 -0300 Message-ID: <20260915173050.3176344-1-qwe.aldo@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260915141547.3010692-1-qwe.aldo@gmail.com> References: <20260915141547.3010692-1-qwe.aldo@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit __vsock_net_mode_string() returns success without updating new_mode when the transfer length is zero. Its caller then reads the uninitialized enum and may permanently store a stack-derived value in the write-once child mode. Return before calling __vsock_net_mode_string() when *lenp is zero so that the helper is never invoked with nothing to parse and new_mode is never read uninitialized. This also prevents an empty write from locking the current mode. Fixes: eafb64f40ca4 ("vsock: add netns to vsock core") Cc: stable@vger.kernel.org Reviewed-by: Luigi Leonardi Signed-off-by: Aldo Ariel Panzardo --- Changes in v3: - Move the !*lenp early return before __vsock_net_mode_string() instead of after it, as suggested by Stefano Garzarella. - Add missing maintainer CCs per get_maintainer.pl. - Add Luigi's Reviewed-by. Changes in v2: - Return early instead of initializing new_mode to the current value, which would silently consume the write-once transition. net/vmw_vsock/af_vsock.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c index 622dbd0467..XXXXXXX 100644 --- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -2879,6 +2879,9 @@ static int vsock_net_child_mode_string(const struct ctl_table *table, int write, net = container_of(table->data, struct net, vsock.child_ns_mode); + if (!*lenp) + return 0; + ret = __vsock_net_mode_string(table, write, buffer, lenp, ppos, vsock_net_child_mode(net), &new_mode); if (ret) -- 2.43.0