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Wed, 11 Nov 2026 14:16:50 -0800 (PST) Received: from localhost ([2a03:2880:9ff:40::]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-37520cfe29fsm21570686eec.21.2026.11.11.14.16.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Nov 2026 14:16:50 -0800 (PST) Date: Wed, 11 Nov 2026 14:16:46 -0800 From: Stanislav Fomichev To: Xia Yan Cc: netdev@vger.kernel.org, edumazet@kernel.org, kuniyu@google.com, pabeni@redhat.com, willemb@google.com, davem@davemloft.net, kuba@kernel.org, horms@kernel.org, asml.silence@gmail.com, kaiyuanz@google.com, linux-kernel@vger.kernel.org, almasrymina@google.com, yana06070@163.com Subject: Re: [PATCH net-next] net: fix token index wraparound in SO_DEVMEM_DONTNEED Message-ID: References: <20261110120331.13661-1-yanxia@cmss.chinamobile.com> X-Mailing-List: linux-kernel@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=utf-8 Content-Disposition: inline In-Reply-To: <20261110120331.13661-1-yanxia@cmss.chinamobile.com> On 11/10, Xia Yan wrote: > SO_DEVMEM_DONTNEED computes each index as token_start + j, in 32-bit > unsigned arithmetic. A start of 0xfffffffe and a count of 4 produce > indices 0xfffffffe, 0xffffffff, 0 and 1. Once the sum wraps, the loop > can erase an existing low-numbered token from the same socket. Sorry, I fail to understand what's the issue. This is (buggy) userspace misusing the api and potentially removing different tokens, right? So what are we fixing? Can you explain more?