From: Simon Horman <horms@kernel.org>
To: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
Cc: Heiner Kallweit <hkallweit1@gmail.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
nic_swsd@realtek.com, "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Marco Elver <elver@google.com>
Subject: Re: [PATCH v4 3/3] r8169: fix the KCSAN reported data race in rtl_rx while reading desc->opts1
Date: Fri, 20 Oct 2023 15:00:23 +0200 [thread overview]
Message-ID: <20231020130023.GF2208164@kernel.org> (raw)
In-Reply-To: <20231018193434.344176-3-mirsad.todorovac@alu.unizg.hr>
On Wed, Oct 18, 2023 at 09:34:38PM +0200, Mirsad Goran Todorovac wrote:
> KCSAN reported the following data-race bug:
>
> ==================================================================
> BUG: KCSAN: data-race in rtl8169_poll (drivers/net/ethernet/realtek/r8169_main.c:4430 drivers/net/ethernet/realtek/r8169_main.c:4583) r8169
>
> race at unknown origin, with read to 0xffff888117e43510 of 4 bytes by interrupt on cpu 21:
> rtl8169_poll (drivers/net/ethernet/realtek/r8169_main.c:4430 drivers/net/ethernet/realtek/r8169_main.c:4583) r8169
> __napi_poll (net/core/dev.c:6527)
> net_rx_action (net/core/dev.c:6596 net/core/dev.c:6727)
> __do_softirq (kernel/softirq.c:553)
> __irq_exit_rcu (kernel/softirq.c:427 kernel/softirq.c:632)
> irq_exit_rcu (kernel/softirq.c:647)
> sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1074 (discriminator 14))
> asm_sysvec_apic_timer_interrupt (./arch/x86/include/asm/idtentry.h:645)
> cpuidle_enter_state (drivers/cpuidle/cpuidle.c:291)
> cpuidle_enter (drivers/cpuidle/cpuidle.c:390)
> call_cpuidle (kernel/sched/idle.c:135)
> do_idle (kernel/sched/idle.c:219 kernel/sched/idle.c:282)
> cpu_startup_entry (kernel/sched/idle.c:378 (discriminator 1))
> start_secondary (arch/x86/kernel/smpboot.c:210 arch/x86/kernel/smpboot.c:294)
> secondary_startup_64_no_verify (arch/x86/kernel/head_64.S:433)
>
> value changed: 0x80003fff -> 0x3402805f
>
> Reported by Kernel Concurrency Sanitizer on:
> CPU: 21 PID: 0 Comm: swapper/21 Tainted: G L 6.6.0-rc2-kcsan-00143-gb5cbe7c00aa0 #41
> Hardware name: ASRock X670E PG Lightning/X670E PG Lightning, BIOS 1.21 04/26/2023
> ==================================================================
>
> drivers/net/ethernet/realtek/r8169_main.c:
> ==========================================
> 4429
> → 4430 status = le32_to_cpu(desc->opts1);
> 4431 if (status & DescOwn)
> 4432 break;
> 4433
> 4434 /* This barrier is needed to keep us from reading
> 4435 * any other fields out of the Rx descriptor until
> 4436 * we know the status of DescOwn
> 4437 */
> 4438 dma_rmb();
> 4439
> 4440 if (unlikely(status & RxRES)) {
> 4441 if (net_ratelimit())
> 4442 netdev_warn(dev, "Rx ERROR. status = %08x\n",
>
> Marco Elver explained that dma_rmb() doesn't prevent the compiler to tear up the access to
> desc->opts1 which can be written to concurrently. READ_ONCE() should prevent that from
> happening:
>
> 4429
> → 4430 status = le32_to_cpu(READ_ONCE(desc->opts1));
> 4431 if (status & DescOwn)
> 4432 break;
> 4433
>
> As the consequence of this fix, this KCSAN warning was eliminated.
>
> Fixes: 6202806e7c03a ("r8169: drop member opts1_mask from struct rtl8169_private")
> Suggested-by: Marco Elver <elver@google.com>
> Cc: Heiner Kallweit <hkallweit1@gmail.com>
> Cc: nic_swsd@realtek.com
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: netdev@vger.kernel.org
> Link: https://lore.kernel.org/lkml/dc7fc8fa-4ea4-e9a9-30a6-7c83e6b53188@alu.unizg.hr/
> Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
> Acked-by: Marco Elver <elver@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
next prev parent reply other threads:[~2023-10-20 13:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-18 19:34 [PATCH v4 1/3] r8169: fix the KCSAN reported data-race in rtl_tx() while reading tp->cur_tx Mirsad Goran Todorovac
2023-10-18 19:34 ` [PATCH v4 2/3] r8169: fix the KCSAN reported data-race in rtl_tx while reading TxDescArray[entry].opts1 Mirsad Goran Todorovac
2023-10-20 13:00 ` Simon Horman
2023-10-18 19:34 ` [PATCH v4 3/3] r8169: fix the KCSAN reported data race in rtl_rx while reading desc->opts1 Mirsad Goran Todorovac
2023-10-20 13:00 ` Simon Horman [this message]
2023-10-20 12:59 ` [PATCH v4 1/3] r8169: fix the KCSAN reported data-race in rtl_tx() while reading tp->cur_tx Simon Horman
2023-10-20 23:50 ` Jakub Kicinski
2023-10-21 16:51 ` Mirsad Goran Todorovac
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