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 3B43E2C0874; Mon, 5 May 2025 22:36:21 +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=1746484582; cv=none; b=kGUMpoEBhe8LSlNnrBzE8VhACAEYmqghsoyLAJ9ZyXDajYR2j5grvYn/8jSm7qwxIY0+rG50zUel4ffb9Neq9hzOOGm087tJJcvxLbKWh+DxJkgh2256DCCOD8jjGJywEUyYrRhcpPTU02JEzjSQ0izoQ7aUJvcHCXj6jhFBNGk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746484582; c=relaxed/simple; bh=sZT6FiZi0p6YPRIkb0191uQc8kanjl/HKruPLOZcNiM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=RIDcRzaKdwp7rlSg981BCkjuaV44PQGo/a7/EFj0kP96I9qOFmQMS1NgYhDU8EB8pKwVV5qNI/MzF/7K5cd7oXJ+P8SkDQw9aD8PlsvKK2yBogRVvn5jCLDEx91l/qw2h6MQNbaNMkZqaIy3AkowXrEO0lkVK4DZnWo7/x0GxxY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Csr+kZh+; 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="Csr+kZh+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 47AAFC4CEEE; Mon, 5 May 2025 22:36:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746484581; bh=sZT6FiZi0p6YPRIkb0191uQc8kanjl/HKruPLOZcNiM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Csr+kZh+hXfVV85ae7jNjr8i1c5dkYqWtxBX/DbGpSY9ZdpzZ8+up3hmTuwWML60C 4pD6fIKvWe5tWZNXlTs0Nb9Zq1acHOw9hnu2EwjzFG2LPni3DF6ZyxlbRAd8ftw3rR YMeCAmMKec86tSplBimO1Z/xq7NNd/pZZwcEbaINR7SWNasEsOmqDrbasKA2Ka63D/ qXC8NeJIONwKWhTRVsJ6BoABKgEa9L9Oj6uLX9zWxX43ogY1+MoY1A+Q6cr+WutE3f pTj1OQKvN+hKKtCJzXjp40AOlq9dtiOaQu3+caP63iq9MoEZYu49T8G/6PP3fDraqv K7aMOSC/jHP5Q== 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, menglong8.dong@gmail.com, gnault@redhat.com, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 6.14 547/642] vxlan: Annotate FDB data races Date: Mon, 5 May 2025 18:12:43 -0400 Message-Id: <20250505221419.2672473-547-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250505221419.2672473-1-sashal@kernel.org> References: <20250505221419.2672473-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.14.5 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/vxlan_core.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c index ae0e2edfde1aa..cdd2a78badf55 100644 --- a/drivers/net/vxlan/vxlan_core.c +++ b/drivers/net/vxlan/vxlan_core.c @@ -227,9 +227,9 @@ static int vxlan_fdb_info(struct sk_buff *skb, struct vxlan_dev *vxlan, be32_to_cpu(fdb->vni))) 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)) @@ -434,8 +434,8 @@ 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; } @@ -1009,12 +1009,12 @@ 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; } } @@ -1048,7 +1048,7 @@ 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) @@ -1481,7 +1481,7 @@ static enum skb_drop_reason 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); @@ -2852,7 +2852,7 @@ 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