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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 v3 1/1] i40e: xsk: advance next_to_clean on status descriptors Date: Thu, 13 Nov 2025 19:24:38 +1100 Message-Id: <20251113082438.54154-2-alessandro.d@gmail.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20251113082438.54154-1-alessandro.d@gmail.com> References: <20251113082438.54154-1-alessandro.d@gmail.com> Precedence: bulk X-Mailing-List: netdev@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. Rename i40e_inc_ntp to i40e_inc_ntp_ntc. Make it take an optional pointer to next_to_clean so it's harder for callers to accidentally forget to advance it. Fixes: 1c9ba9c14658 ("i40e: xsk: add RX multi-buffer support") Signed-off-by: Alessandro Decina --- drivers/net/ethernet/intel/i40e/i40e_txrx.c | 33 ++++++++++++------- .../ethernet/intel/i40e/i40e_txrx_common.h | 2 ++ drivers/net/ethernet/intel/i40e/i40e_xsk.c | 17 ++++++---- 3 files changed, 34 insertions(+), 18 deletions(-) diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c index cc0b9efc2637..d3dae895a058 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c @@ -2359,15 +2359,24 @@ void i40e_finalize_xdp_rx(struct i40e_ring *rx_ring, unsigned int xdp_res) } /** - * i40e_inc_ntp: Advance the next_to_process index + * i40e_inc_ntp_ntc: Advance the next_to_process and next_to_clean indexes * @rx_ring: Rx ring + * @next_to_process: Pointer to next_to_process + * @next_to_clean: Pointer to next_to_clean or NULL + * + * This function advances the next_to_process index. If next_to_clean is not + * NULL, it is advanced as well. **/ -static void i40e_inc_ntp(struct i40e_ring *rx_ring) +void i40e_inc_ntp_ntc(struct i40e_ring *rx_ring, u16 *next_to_process, + u16 *next_to_clean) { - u32 ntp = rx_ring->next_to_process + 1; + u16 ntp = *next_to_process + 1; ntp = (ntp < rx_ring->count) ? ntp : 0; - rx_ring->next_to_process = ntp; + *next_to_process = ntp; + if (next_to_clean) + *next_to_clean = ntp; + prefetch(I40E_RX_DESC(rx_ring, ntp)); } @@ -2484,17 +2493,19 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget, i40e_clean_programming_status(rx_ring, rx_desc->raw.qword[0], qword); + bool eop; + rx_buffer = i40e_rx_bi(rx_ring, ntp); - i40e_inc_ntp(rx_ring); - i40e_reuse_rx_page(rx_ring, rx_buffer); /* Update ntc and bump cleaned count if not in the * middle of mb packet. */ - if (rx_ring->next_to_clean == ntp) { - rx_ring->next_to_clean = - rx_ring->next_to_process; + eop = rx_ring->next_to_process == + rx_ring->next_to_clean; + i40e_inc_ntp_ntc(rx_ring, &rx_ring->next_to_process, + eop ? &rx_ring->next_to_clean : NULL); + if (eop) cleaned_count++; - } + i40e_reuse_rx_page(rx_ring, rx_buffer); continue; } @@ -2507,7 +2518,7 @@ static int i40e_clean_rx_irq(struct i40e_ring *rx_ring, int budget, rx_buffer = i40e_get_rx_buffer(rx_ring, size); neop = i40e_is_non_eop(rx_ring, rx_desc); - i40e_inc_ntp(rx_ring); + i40e_inc_ntp_ntc(rx_ring, &rx_ring->next_to_process, NULL); if (!xdp->data) { unsigned char *hard_start; diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx_common.h b/drivers/net/ethernet/intel/i40e/i40e_txrx_common.h index e26807fd2123..3d7e4b3404f0 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_txrx_common.h +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx_common.h @@ -17,6 +17,8 @@ void i40e_update_rx_stats(struct i40e_ring *rx_ring, unsigned int total_rx_packets); void i40e_finalize_xdp_rx(struct i40e_ring *rx_ring, unsigned int xdp_res); void i40e_release_rx_desc(struct i40e_ring *rx_ring, u32 val); +void i40e_inc_ntp_ntc(struct i40e_ring *rx_ring, u16 *next_to_process, + u16 *next_to_clean); #define I40E_XDP_PASS 0 #define I40E_XDP_CONSUMED BIT(0) diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c index 9f47388eaba5..fdf72446ed67 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c +++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c @@ -410,7 +410,6 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) u16 next_to_clean = rx_ring->next_to_clean; unsigned int xdp_res, xdp_xmit = 0; struct xdp_buff *first = NULL; - u32 count = rx_ring->count; struct bpf_prog *xdp_prog; u32 entries_to_alloc; bool failure = false; @@ -430,6 +429,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) struct xdp_buff *bi; unsigned int size; u64 qword; + bool neop; rx_desc = I40E_RX_DESC(rx_ring, next_to_process); qword = le64_to_cpu(rx_desc->wb.qword1.status_error_len); @@ -446,8 +446,10 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) qword); bi = *i40e_rx_bi(rx_ring, next_to_process); xsk_buff_free(bi); - if (++next_to_process == count) - next_to_process = 0; + i40e_inc_ntp_ntc(rx_ring, &next_to_process, + next_to_process == next_to_clean ? + &next_to_clean : + NULL); continue; } @@ -466,16 +468,17 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) break; } - if (++next_to_process == count) - next_to_process = 0; + neop = i40e_is_non_eop(rx_ring, rx_desc); + // advance next_to_process. on EOP, advance next_to_clean as well. + i40e_inc_ntp_ntc(rx_ring, &next_to_process, + !neop ? &next_to_clean : NULL); - if (i40e_is_non_eop(rx_ring, rx_desc)) + if (neop) continue; xdp_res = i40e_run_xdp_zc(rx_ring, first, xdp_prog); i40e_handle_xdp_result_zc(rx_ring, first, rx_desc, &rx_packets, &rx_bytes, xdp_res, &failure); - next_to_clean = next_to_process; if (failure) break; total_rx_packets += rx_packets; -- 2.43.0