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([2a01:4b00:bd21:4f00:7cc6:d3ca:494:116c]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4856eaa4fb0sm26849855e9.12.2026.03.16.16.22.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Mar 2026 16:22:53 -0700 (PDT) Message-ID: <231361d3-dfaa-422d-a246-03f9a51b89f2@gmail.com> Date: Mon, 16 Mar 2026 23:22:46 +0000 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: cast id to u64 before shifting in io_allocate_rbuf_ring() To: Jens Axboe , Anas Iqbal Cc: io-uring@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260316150636.2123-1-mohd.abd.6602@gmail.com> <1f79957a-5b23-4bbd-af8d-9d1c86791645@kernel.dk> Content-Language: en-US From: Pavel Begunkov In-Reply-To: <1f79957a-5b23-4bbd-af8d-9d1c86791645@kernel.dk> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/16/26 19:37, Jens Axboe wrote: > On 3/16/26 9:06 AM, Anas Iqbal wrote: >> Smatch warns: >> io_uring/zcrx.c:393 io_allocate_rbuf_ring() warn: should 'id << 16' be a 64 bit type? >> >> The expression 'id << IORING_OFF_PBUF_SHIFT' is evaluated using 32-bit >> arithmetic because id is a u32. This may overflow before being promoted >> to the 64-bit mmap_offset. >> >> Cast id to u64 before shifting to ensure the shift is performed in >> 64-bit arithmetic. > > I'd be impressed if 'id' could be large enough to cause this to > overflow. AFAICT, you'd need more than 64K interface queues registered > to hit this. So I think this should be reframed as a cleanup, to appease > smatch. Pretty much so. I'll queue up the patch targeting 7.1, thanks -- Pavel Begunkov