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Sun, 18 Oct 2026 15:13:29 -0700 (PDT) Date: Sun, 18 Oct 2026 18:13:26 -0400 From: "Michael S. Tsirkin" To: Linus Torvalds Cc: David Laight , Haoran Wang , jasowangio@gmail.com, KVM list , virtualization@lists.linux.dev, Netdev , Eugenio =?iso-8859-1?Q?P=E9rez?= , Linux Kernel Mailing List , Security Officers Subject: Re: [BUG] vhost/vringh: __get_user without access_ok leaks kernel memory via vDPA passthrough Message-ID: <20261018181202-mutt-send-email-mst@kernel.org> References: <6ad07f8a.a0c71a5e.2d2efd.977a@mx.google.com> <20261018152358-mutt-send-email-mst@kernel.org> <20261018204838.4080b238@pumpkin> <20261018175347-mutt-send-email-mst@kernel.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Sun, Oct 18, 2026 at 12:06:36PM -1000, Linus Torvalds wrote: > > > > + > > > > +           if (!access_ok(uaddr, sizeof(*p))) > > > > +                   return -EFAULT; > > > > +           ret = __get_user(tmp, uaddr); > > > > > > Can't that be a normal get_user() call? > > > > > > David > > > > Ugh, actually no. This is called under local_bh_disable. > > > > get_user would splat on might_sleep. > I[ sorry for html - driving around ] > > That's a separate bug, and you really shouldn't use __get_user to work around > it just because it doesn't check.  > > You should use pagefault_disable() around the access. And if there is still a > sleep_on() complaint, that should be fixed.  > >         Linus Thanks Linus, will look into this. -- MST