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Fri, 24 Jul 2026 20:00:26 -0700 (PDT) From: "Cen Zhang (Microsoft)" To: sdf.kernel@gmail.com Cc: AutonomousCodeSecurity@microsoft.com, blbllhy@gmail.com, bpf@vger.kernel.org, davem@davemloft.net, edumazet@google.com, horms@kernel.org, kuba@kernel.org, kys@microsoft.com, linux-kernel@vger.kernel.org, maciej.fijalkowski@intel.com, magnus.karlsson@intel.com, netdev@vger.kernel.org, pabeni@redhat.com, sdf@fomichev.me, tgopinath@linux.microsoft.com Subject: Re: [PATCH net] xsk: fix NULL pointer dereference in __xsk_rcv() Date: Fri, 24 Jul 2026 23:00:26 -0400 Message-ID: <20260725030026.191412-1-blbllhy@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > ... which means they are "lost"? You are right. The UMEM frames already consumed from the Fill Ring must be recycled into free_list when the packet cannot be completed. Since the current loop calls __xsk_rcv_zc_safe(), and therefore xp_release(), after every allocation, they cannot simply be recycled after a later failure. I will rework v2 as a two-stage transaction: first allocate and stage all required buffers, recycling all staged buffers if any allocation fails; then run the error-free copy/submit/release loop only after the allocation stage succeeds. Thanks.