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Miller" , Alexei Starovoitov , Andrew Lunn , Daniel Borkmann , Eric Dumazet , Jakub Kicinski , Jesper Dangaard Brouer , John Fastabend , Paolo Abeni , Przemek Kitszel , Stanislav Fomichev , Tirthendu Sarkar , Tony Nguyen , bpf@vger.kernel.org, intel-wired-lan@lists.osuosl.org, linux-kernel@vger.kernel.org, Alessandro Decina Subject: [PATCH net v2 1/1] i40e: xsk: advance next_to_clean on status descriptors Date: Wed, 22 Oct 2025 00:32:00 +0700 Message-Id: <20251021173200.7908-2-alessandro.d@gmail.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20251021173200.7908-1-alessandro.d@gmail.com> References: <20251021173200.7908-1-alessandro.d@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Whenever a status descriptor is received, i40e processes and skips over it, correctly updating next_to_process but forgetting to update next_to_clean. In the next iteration this accidentally causes the creation of an invalid multi-buffer xdp_buff where the first fragment is the status descriptor. If then a skb is constructed from such an invalid buffer - because the eBPF program returns XDP_PASS - a panic occurs: [ 5866.367317] BUG: unable to handle page fault for address: ffd31c37eab1c980 [ 5866.375050] #PF: supervisor read access in kernel mode [ 5866.380825] #PF: error_code(0x0000) - not-present page [ 5866.386602] PGD 0 [ 5866.388867] Oops: Oops: 0000 [#1] SMP NOPTI [ 5866.393575] CPU: 34 UID: 0 PID: 0 Comm: swapper/34 Not tainted 6.17.0-custom #1 PREEMPT(voluntary) [ 5866.403740] Hardware name: Supermicro AS -2115GT-HNTR/H13SST-G, BIOS 3.2 03/20/2025 [ 5866.412339] RIP: 0010:memcpy+0x8/0x10 [ 5866.416454] Code: cc cc 90 cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 90 48 89 f8 48 89 d1 a4 e9 fc 26 c0 fe 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 [ 5866.437538] RSP: 0018:ff428d9ec0bb0ca8 EFLAGS: 00010286 [ 5866.443415] RAX: ff2dd26dbd8f0000 RBX: ff2dd265ad161400 RCX: 00000000000004e1 [ 5866.451435] RDX: 00000000000004e1 RSI: ffd31c37eab1c980 RDI: ff2dd26dbd8f0000 [ 5866.459454] RBP: ff428d9ec0bb0d40 R08: 0000000000000000 R09: 0000000000000000 [ 5866.467470] R10: 0000000000000000 R11: 0000000000000000 R12: ff428d9eec726ef8 [ 5866.475490] R13: ff2dd26dbd8f0000 R14: ff2dd265ca2f9fc0 R15: ff2dd26548548b80 [ 5866.483509] FS: 0000000000000000(0000) GS:ff2dd2c363592000(0000) knlGS:0000000000000000 [ 5866.492600] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 5866.499060] CR2: ffd31c37eab1c980 CR3: 0000000178d7b040 CR4: 0000000000f71ef0 [ 5866.507079] PKRU: 55555554 [ 5866.510125] Call Trace: [ 5866.512867] [ 5866.515132] ? i40e_clean_rx_irq_zc+0xc50/0xe60 [i40e] [ 5866.520921] i40e_napi_poll+0x2d8/0x1890 [i40e] [ 5866.526022] ? srso_alias_return_thunk+0x5/0xfbef5 [ 5866.531408] ? raise_softirq+0x24/0x70 [ 5866.535623] ? srso_alias_return_thunk+0x5/0xfbef5 [ 5866.541011] ? srso_alias_return_thunk+0x5/0xfbef5 [ 5866.546397] ? rcu_sched_clock_irq+0x225/0x1800 [ 5866.551493] __napi_poll+0x30/0x230 [ 5866.555423] net_rx_action+0x20b/0x3f0 [ 5866.559643] handle_softirqs+0xe4/0x340 [ 5866.563962] __irq_exit_rcu+0x10e/0x130 [ 5866.568283] irq_exit_rcu+0xe/0x20 [ 5866.572110] common_interrupt+0xb6/0xe0 [ 5866.576425] [ 5866.578791] Advance next_to_clean to ensure invalid xdp_buff(s) aren't created. Fixes: 1c9ba9c14658 ("i40e: xsk: add RX multi-buffer support") Signed-off-by: Alessandro Decina --- drivers/net/ethernet/intel/i40e/i40e_xsk.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c index 9f47388eaba5..dbc19083bbb7 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c +++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c @@ -441,13 +441,18 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) dma_rmb(); if (i40e_rx_is_programming_status(qword)) { + u16 ntp; + i40e_clean_programming_status(rx_ring, rx_desc->raw.qword[0], qword); bi = *i40e_rx_bi(rx_ring, next_to_process); xsk_buff_free(bi); - if (++next_to_process == count) + ntp = next_to_process++; + if (next_to_process == count) next_to_process = 0; + if (next_to_clean == ntp) + next_to_clean = next_to_process; continue; } -- 2.43.0