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Mon, 09 Nov 2026 02:04:53 -0800 (PST) Received: from localhost.localdomain ([2406:7400:51:5a62:c2b6:f9ff:fe77:10a0]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-372667d60absm12886710eec.26.2026.11.09.02.04.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Nov 2026 02:04:53 -0800 (PST) From: Amaan Cheval To: netdev@vger.kernel.org Cc: joshwash@google.com, hramamurthy@google.com, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, bcf@google.com, jordanrhee@google.com, przemyslaw.kitszel@intel.com, maciej.fijalkowski@intel.com, pkaligineedi@google.com, maolson@google.com, csully@google.com, willemb@google.com, yangchun@google.com, npl@google.com, awogbemila@google.com, shailend@google.com, nktgrg@google.com, maxyuan@google.com, bpf@vger.kernel.org, john.fastabend@gmail.com, hawk@kernel.org, sdf@fomichev.me, daniel@iogearbox.net, ast@kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Amaan Cheval Subject: [PATCH net v5 0/2] gve: fix RX page refcount overflow with the pagecnt bias Date: Mon, 9 Nov 2026 15:34:35 +0530 Message-ID: <20261109100437.331423-1-amaan.cheval@gmail.com> X-Mailer: git-send-email 2.49.0 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-Transfer-Encoding: 8bit gve's GQI and DQO-QPL RX paths bias every RX page's refcount to INT_MAX, so a single get_page() from the stack, e.g. splice() of received data, overflows it: splice/tee fail with EIO/EFAULT and GQI can reset the NIC. Patch 2 lowers the bias to USHRT_MAX, as other drivers do. With the smaller bias the driver gives up its last reference on a page once every USHRT_MAX handoffs instead of once every INT_MAX, which is only safe while every consumer holds its reference until the buffer is recycled. That is not the case for an XDP_REDIRECT from DQO-QPL to an AF_XDP socket in copy mode, a path the driver never meant to support: commit d8a8ca14c937 dropped the queue_format check that used to refuse it. Patch 1 refuses XDP on any queue format the driver advertises no XDP features for, which today means DQO-QPL, so patch 2 depends on it. Trees before 6.17 still have the old check, so there patch 2 stands alone. Harshitha mentioned on v2 that Google would send a patch blocking XDP on DQO-QPL; if one is already in flight I'm happy to drop patch 1 in its favour. v5: - Patch 1: check dev->xdp_features instead of queue_format, and reword the subject and message around that (Joshua). - Patch 2: name INT_MAX in the subject. No code change. v4: https://lore.kernel.org/netdev/20261106114551.212675-1-amaan.cheval@gmail.com/ - Add patch 1/2 blocking XDP on DQO-QPL (Sashiko). - Say "overflow" instead of "headroom"; use USHRT_MAX directly instead of a macro (Maciej). - Say which trees need patch 1, for stable. v3: https://lore.kernel.org/netdev/20261103090651.35399-1-amaan.cheval@gmail.com/ v2: https://lore.kernel.org/netdev/20261102112613.18334-1-amaan.cheval@gmail.com/ v1: https://lore.kernel.org/netdev/20261031173449.2439047-1-amaan.cheval@gmail.com/ Amaan Cheval (2): gve: refuse XDP on queue formats without XDP support gve: fix RX page refcount overflow from INT_MAX pagecnt_bias drivers/net/ethernet/google/gve/gve.h | 2 +- .../net/ethernet/google/gve/gve_buffer_mgmt_dqo.c | 4 ++-- drivers/net/ethernet/google/gve/gve_main.c | 6 ++++++ drivers/net/ethernet/google/gve/gve_rx.c | 8 ++++---- drivers/net/ethernet/google/gve/gve_utils.c | 12 ++++-------- drivers/net/ethernet/google/gve/gve_utils.h | 2 +- 6 files changed, 18 insertions(+), 16 deletions(-) base-commit: 21f57ec673a1917547c808cfa81890485fffa03b -- 2.47.3