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Miller" , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-17.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, ENV_AND_HDR_SPF_MATCH,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL,USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (howler.vger.email [0.0.0.0]); Mon, 18 Sep 2023 00:44:27 -0700 (PDT) On Mon, Sep 18, 2023 at 8:15=E2=80=AFAM Mirsad Todorovac wrote: > > Hi all, > > In the vanilla torvalds tree kernel on Ubuntu 22.04, commit 6.6.0-rc1-kcs= an-00269-ge789286468a9, > KCSAN discovered a data-race in rtl8169_poll(): > > [ 9591.740976] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > [ 9591.740990] BUG: KCSAN: data-race in rtl8169_poll (drivers/net/etherne= t/realtek/r8169_main.c:4430 drivers/net/ethernet/realtek/r8169_main.c:4583)= r8169 > > [ 9591.741060] race at unknown origin, with read to 0xffff888109773130 of= 4 bytes by interrupt on cpu 21: > [ 9591.741073] rtl8169_poll (drivers/net/ethernet/realtek/r8169_main.c:44= 30 drivers/net/ethernet/realtek/r8169_main.c:4583) r8169 > [ 9591.741135] __napi_poll (net/core/dev.c:6527) > [ 9591.741149] net_rx_action (net/core/dev.c:6596 net/core/dev.c:6727) > [ 9591.741161] __do_softirq (kernel/softirq.c:553) > [ 9591.741175] __irq_exit_rcu (kernel/softirq.c:427 kernel/softirq.c:632) > [ 9591.741185] irq_exit_rcu (kernel/softirq.c:647) > [ 9591.741194] common_interrupt (arch/x86/kernel/irq.c:247 (discriminator= 14)) > [ 9591.741206] asm_common_interrupt (./arch/x86/include/asm/idtentry.h:63= 6) > [ 9591.741217] cpuidle_enter_state (drivers/cpuidle/cpuidle.c:291) > [ 9591.741227] cpuidle_enter (drivers/cpuidle/cpuidle.c:390) > [ 9591.741237] call_cpuidle (kernel/sched/idle.c:135) > [ 9591.741249] do_idle (kernel/sched/idle.c:219 kernel/sched/idle.c:282) > [ 9591.741259] cpu_startup_entry (kernel/sched/idle.c:378 (discriminator = 1)) > [ 9591.741268] start_secondary (arch/x86/kernel/smpboot.c:210 arch/x86/ke= rnel/smpboot.c:294) > [ 9591.741281] secondary_startup_64_no_verify (arch/x86/kernel/head_64.S:= 433) > > [ 9591.741300] value changed: 0x80003fff -> 0x34044510 > > [ 9591.741314] Reported by Kernel Concurrency Sanitizer on: > [ 9591.741322] CPU: 21 PID: 0 Comm: swapper/21 Tainted: G L = 6.6.0-rc1-kcsan-00269-ge789286468a9-dirty #4 > [ 9591.741334] Hardware name: ASRock X670E PG Lightning/X670E PG Lightnin= g, BIOS 1.21 04/26/2023 > [ 9591.741343] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > (The taint is not from the proprietary module, but triggered from the pre= vious reported and unfixed bug.) > > Apparently, it is this code: > > static int rtl8169_poll(struct napi_struct *napi, int budget) > { > struct rtl8169_private *tp =3D container_of(napi, struct rtl8169_= private, napi); > struct net_device *dev =3D tp->dev; > int work_done; > > rtl_tx(dev, tp, budget); > > =E2=86=92 work_done =3D rtl_rx(dev, tp, budget); > > if (work_done < budget && napi_complete_done(napi, work_done)) > rtl_irq_enable(tp); > > return work_done; > } > > and > > static int rtl_rx(struct net_device *dev, struct rtl8169_private *tp, int= budget) > { > struct device *d =3D tp_to_dev(tp); > int count; > > for (count =3D 0; count < budget; count++, tp->cur_rx++) { > unsigned int pkt_size, entry =3D tp->cur_rx % NUM_RX_DESC= ; > struct RxDesc *desc =3D tp->RxDescArray + entry; > struct sk_buff *skb; > const void *rx_buf; > dma_addr_t addr; > u32 status; > > =E2=86=92 status =3D le32_to_cpu(desc->opts1); > if (status & DescOwn) > break; > > /* This barrier is needed to keep us from reading > * any other fields out of the Rx descriptor until > * we know the status of DescOwn > */ > dma_rmb(); > > if (unlikely(status & RxRES)) { > . > . > . > > The reason isn't obvious, so it might be interesting if this is a valid r= eport and whether it caused spurious corruption > of the network data on Realtek 8169 compatible cards ... > I think this is pretty much expected. Driver reads a piece of memory that the hardware can modify. Adding data_race() annotations could avoid these false positives. > Hope this helps. > > Best regards, > Mirsad Todorovac