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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e1d80f9b3sm4629943f8f.20.2026.10.20.02.21.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Oct 2026 02:21:35 -0700 (PDT) Date: Tue, 20 Oct 2026 10:21:34 +0100 From: David Laight To: Linus Torvalds Cc: "Michael S. Tsirkin" , Wang Haoran , jasowangio@gmail.com, kvm@vger.kernel.org, virtualization@lists.linux.dev, netdev@vger.kernel.org, eperezma@redhat.com Subject: Re: [BUG] vhost/vringh: __get_user without access_ok leaks kernel memory via vDPA passthrough Message-ID: <20261020102134.745ff48a@pumpkin> In-Reply-To: References: <6ad07f8a.a0c71a5e.2d2efd.977a@mx.google.com> <20261018152358-mutt-send-email-mst@kernel.org> <20261018174250-mutt-send-email-mst@kernel.org> <376ef9d0-b03f-4f85-aee5-46cf20eb00ae@gmail.com> <20261020021924-mutt-send-email-mst@kernel.org> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) X-Mailing-List: kvm@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 19 Oct 2026 20:51:43 -1000 Linus Torvalds wrote: > On Mon, 19 Oct 2026 at 20:31, Michael S. Tsirkin wrote: > > > > The following seems to work for me. Testing would be appreciated. > > I have a whole branch that removes __get_user() and __put_user() entirely. There should also be very few (if any) access_ok() calls outside of the code that implements user copies. David > > Somebody should check that I did it right. But I didn't want to do the > pagefault_disable() around the vringh_notify() part, so it's not quite > the same as yours. > > Let me just push it out. I was going to let it simmer, but your email > made me go "I should just let more people look at it". > > Mind taking a look at the 'uaccess-cleanups' branch? > > It builds for me. That's all the testing it has gotten so far. Blush. > > Linus >