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Wed, 22 Jan 2025 16:18:23 -0800 (PST) Message-ID: <4bf7e5d1-4e66-496d-a503-5dc349efe398@kernel.dk> Date: Wed, 22 Jan 2025 17:18:22 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] io_uring/uring_cmd: add missing READ_ONCE() on shared memory read From: Jens Axboe To: Pavel Begunkov , Jann Horn Cc: io-uring@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250121-uring-sockcmd-fix-v1-1-add742802a29@google.com> <173757472950.267317.14676213787840454554.b4-ty@kernel.dk> Content-Language: en-US In-Reply-To: <173757472950.267317.14676213787840454554.b4-ty@kernel.dk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 1/22/25 12:38 PM, Jens Axboe wrote: > > On Tue, 21 Jan 2025 17:09:59 +0100, Jann Horn wrote: >> cmd->sqe seems to point to shared memory here; so values should only be >> read from it with READ_ONCE(). To ensure that the compiler won't generate >> code that assumes the value in memory will stay constant, add a >> READ_ONCE(). >> The callees io_uring_cmd_getsockopt() and io_uring_cmd_setsockopt() already >> do this correctly. >> >> [...] > > Applied, thanks! > > [1/1] io_uring/uring_cmd: add missing READ_ONCE() on shared memory read > commit: 0963dba3dc006b454c54fd019bbbdb931e7a7c70 I took a closer look and this isn't necessary. Either ->sqe is a full copy at this point. Should probably be renamed as such... If we want to make this clearer, then we should do: - switch (cmd->sqe->cmd_op) { + switch (cmd->cmd_op) { instead. I'll drop this one. -- Jens Axboe