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[79.53.30.11]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4870bf1fad3sm7165977f8f.12.2026.09.16.08.38.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Sep 2026 08:38:40 -0700 (PDT) Date: Wed, 16 Sep 2026 17:38:28 +0200 From: Stefano Garzarella To: Aldo Ariel Panzardo 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 Subject: Re: [PATCH v3] vsock: ignore empty child namespace mode writes Message-ID: References: <20260915141547.3010692-1-qwe.aldo@gmail.com> <20260915173050.3176344-1-qwe.aldo@gmail.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20260915173050.3176344-1-qwe.aldo@gmail.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: gsQW6XyGlJHiaC5Gemy-gz3xJE-25EpOx-gnOnEUtPs_1789573121 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline On Tue, Sep 15, 2026 at 02:30:50PM -0300, Aldo Ariel Panzardo wrote: >__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; >+ I would have moved it even before the net assignmet, but in any case, it doesn't make much difference: Reviewed-by: Stefano Garzarella