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Wed, 16 Sep 2026 09:53:45 -0700 (PDT) Date: Wed, 16 Sep 2026 09:53:33 -0700 From: Bobby Eshleman To: Aldo Ariel Panzardo Cc: Stefano Garzarella , 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: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260915173050.3176344-1-qwe.aldo@gmail.com> 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; > + > ret = __vsock_net_mode_string(table, write, buffer, lenp, ppos, > vsock_net_child_mode(net), &new_mode); > if (ret) > > -- > 2.43.0 Reviewed-by: Bobby Eshleman