From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E392B3C088F; Mon, 5 May 2025 23:23:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746487433; cv=none; b=UyzuYG8XUPAx6q/kJuJ3pUTaidfd+TPr45CRFwM/LXUrrIkRRMVBq31q3J07Gh1VBHUYaqOU9ZsxoQ8nDxR265oB+vTfDs83l7aSlqwgRz1J5HrTCj8t+3dtdx9wPJlWxF/Xzb7V1snzesGapMLDkbjPSbWqgLRgycd8TsMgBJU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746487433; c=relaxed/simple; bh=VqAjdqFowdMxBwvZn1FNxrrbYAYPH2ZoKKabX/YN78c=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=p9wyGoqSCVM9xiRnFVvxXOHdflOoo/hXV9PczEPphtnBNTzyBSkM0x5qOdQzJ45jmM94gM4Dv5eZXQoiVLyETGrmK5QlpSkd1yhjpHHsRq16kVoEFHWnIhX0K1+IX5X+hVuBD9o8tU4gOfhQ3ELHJRGh0CpCRW6OCoOxbKZDmBU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=D6LmhY75; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="D6LmhY75" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 81866C4CEEE; Mon, 5 May 2025 23:23:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746487431; bh=VqAjdqFowdMxBwvZn1FNxrrbYAYPH2ZoKKabX/YN78c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D6LmhY75C9YditeDX/dEhKgDe1QNaLBnE/gCXqt5Q59itSHzCyL4fLRH5gaPvGwG7 8MLPPdnn3bvmy+q1mdhHF8do+ARQ1tjRW5BzI1xhFpdM2Hbo+5yqoQzEP6rZQhpEik E1RkmX65OBH/qDchkEKIAM8jeXPrYjv2f3zNGRnjx3VgOG7HZyYMB9pN+5/CmxZ/uj 8WuBXVcovu701ihhusD8QvLuAEd2sP/YKjxY37yLxJL1GzNFljWLlvv73hw03OaVta o1KkvhUdkhbpjffaypGroGnN7ARDNGedbdK3jvO3oTh2BQSM0WlnIIW9aOYNhuKrvO yGQGWIsRxSB9w== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Ido Schimmel , Petr Machata , Eric Dumazet , Nikolay Aleksandrov , Jakub Kicinski , Sasha Levin , andrew+netdev@lunn.ch, davem@davemloft.net, pabeni@redhat.com, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 68/79] vxlan: Annotate FDB data races Date: Mon, 5 May 2025 19:21:40 -0400 Message-Id: <20250505232151.2698893-68-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250505232151.2698893-1-sashal@kernel.org> References: <20250505232151.2698893-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.4.293 Content-Transfer-Encoding: 8bit From: Ido Schimmel [ Upstream commit f6205f8215f12a96518ac9469ff76294ae7bd612 ] The 'used' and 'updated' fields in the FDB entry structure can be accessed concurrently by multiple threads, leading to reports such as [1]. Can be reproduced using [2]. Suppress these reports by annotating these accesses using READ_ONCE() / WRITE_ONCE(). [1] BUG: KCSAN: data-race in vxlan_xmit / vxlan_xmit write to 0xffff942604d263a8 of 8 bytes by task 286 on cpu 0: vxlan_xmit+0xb29/0x2380 dev_hard_start_xmit+0x84/0x2f0 __dev_queue_xmit+0x45a/0x1650 packet_xmit+0x100/0x150 packet_sendmsg+0x2114/0x2ac0 __sys_sendto+0x318/0x330 __x64_sys_sendto+0x76/0x90 x64_sys_call+0x14e8/0x1c00 do_syscall_64+0x9e/0x1a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffff942604d263a8 of 8 bytes by task 287 on cpu 2: vxlan_xmit+0xadf/0x2380 dev_hard_start_xmit+0x84/0x2f0 __dev_queue_xmit+0x45a/0x1650 packet_xmit+0x100/0x150 packet_sendmsg+0x2114/0x2ac0 __sys_sendto+0x318/0x330 __x64_sys_sendto+0x76/0x90 x64_sys_call+0x14e8/0x1c00 do_syscall_64+0x9e/0x1a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x00000000fffbac6e -> 0x00000000fffbac6f Reported by Kernel Concurrency Sanitizer on: CPU: 2 UID: 0 PID: 287 Comm: mausezahn Not tainted 6.13.0-rc7-01544-gb4b270f11a02 #5 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014 [2] #!/bin/bash set +H echo whitelist > /sys/kernel/debug/kcsan echo !vxlan_xmit > /sys/kernel/debug/kcsan ip link add name vx0 up type vxlan id 10010 dstport 4789 local 192.0.2.1 bridge fdb add 00:11:22:33:44:55 dev vx0 self static dst 198.51.100.1 taskset -c 0 mausezahn vx0 -a own -b 00:11:22:33:44:55 -c 0 -q & taskset -c 2 mausezahn vx0 -a own -b 00:11:22:33:44:55 -c 0 -q & Reviewed-by: Petr Machata Signed-off-by: Ido Schimmel Reviewed-by: Eric Dumazet Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20250204145549.1216254-2-idosch@nvidia.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/vxlan.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index ce11fb2b05561..7105ac37f341e 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -302,9 +302,9 @@ static int vxlan_fdb_info(struct sk_buff *skb, struct vxlan_dev *vxlan, nla_put_u32(skb, NDA_IFINDEX, rdst->remote_ifindex)) goto nla_put_failure; - ci.ndm_used = jiffies_to_clock_t(now - fdb->used); + ci.ndm_used = jiffies_to_clock_t(now - READ_ONCE(fdb->used)); ci.ndm_confirmed = 0; - ci.ndm_updated = jiffies_to_clock_t(now - fdb->updated); + ci.ndm_updated = jiffies_to_clock_t(now - READ_ONCE(fdb->updated)); ci.ndm_refcnt = 0; if (nla_put(skb, NDA_CACHEINFO, sizeof(ci), &ci)) @@ -510,8 +510,8 @@ static struct vxlan_fdb *vxlan_find_mac(struct vxlan_dev *vxlan, struct vxlan_fdb *f; f = __vxlan_find_mac(vxlan, mac, vni); - if (f && f->used != jiffies) - f->used = jiffies; + if (f && READ_ONCE(f->used) != jiffies) + WRITE_ONCE(f->used, jiffies); return f; } @@ -942,12 +942,12 @@ static int vxlan_fdb_update_existing(struct vxlan_dev *vxlan, !(f->flags & NTF_VXLAN_ADDED_BY_USER)) { if (f->state != state) { f->state = state; - f->updated = jiffies; + WRITE_ONCE(f->updated, jiffies); notify = 1; } if (f->flags != fdb_flags) { f->flags = fdb_flags; - f->updated = jiffies; + WRITE_ONCE(f->updated, jiffies); notify = 1; } } @@ -974,7 +974,7 @@ static int vxlan_fdb_update_existing(struct vxlan_dev *vxlan, } if (ndm_flags & NTF_USE) - f->used = jiffies; + WRITE_ONCE(f->used, jiffies); if (notify) { if (rd == NULL) @@ -1351,7 +1351,7 @@ static bool vxlan_snoop(struct net_device *dev, src_mac, &rdst->remote_ip.sa, &src_ip->sa); rdst->remote_ip = *src_ip; - f->updated = jiffies; + WRITE_ONCE(f->updated, jiffies); vxlan_fdb_notify(vxlan, f, rdst, RTM_NEWNEIGH, true, NULL); } else { u32 hash_index = fdb_head_index(vxlan, src_mac, vni); @@ -2748,7 +2748,7 @@ static void vxlan_cleanup(struct timer_list *t) if (f->flags & NTF_EXT_LEARNED) continue; - timeout = f->used + vxlan->cfg.age_interval * HZ; + timeout = READ_ONCE(f->used) + vxlan->cfg.age_interval * HZ; if (time_before_eq(timeout, jiffies)) { netdev_dbg(vxlan->dev, "garbage collect %pM\n", -- 2.39.5