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[73.158.218.242]) by smtp.gmail.com with UTF8SMTPSA id d2e1a72fcca58-742a96e58a9sm6304089b3a.34.2025.05.19.07.41.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 May 2025 07:41:53 -0700 (PDT) Date: Mon, 19 May 2025 07:41:52 -0700 From: Stanislav Fomichev To: Pavel Begunkov Cc: netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, sagi@grimberg.me, willemb@google.com, almasrymina@google.com, kaiyuanz@google.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next] net: devmem: drop iterator type check Message-ID: References: <20250516225441.527020-1-stfomichev@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=utf-8 Content-Disposition: inline In-Reply-To: On 05/19, Pavel Begunkov wrote: > On 5/16/25 23:54, Stanislav Fomichev wrote: > > sendmsg() with a single iov becomes ITER_UBUF, sendmsg() with multiple > > iovs becomes ITER_IOVEC. Instead of adjusting the check to include > > ITER_UBUF, drop the check completely. The callers are guaranteed > > to happen from system call side and we don't need to pay runtime > > cost to verify it. > > I asked for this because io_uring can pass bvecs. Only sendzc can > pass that with cmsg, so probably you won't be able to hit any > real issue, but io_uring needs and soon will have bvec support for > normal sends as well. One can argue we should care as it isn't > merged yet, but there is something very very wrong if an unrelated > and legal io_uring change is able to open a vulnerability in the > devmem path. Any reason not to filter these out on the io_uring side? Or you'll have to interpret sendmsg flags again which is not nice?