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 030A225A323; Tue, 27 May 2025 17:09:16 +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=1748365756; cv=none; b=AhNopc6KDo3AZ78JmAOXz6D4EIOYl+z2lLbp2GY/Y91YXwzAq29YBM6nUAS8zYisJhe/XcgHIHbtl8hKl1iLJN1A8vAeGQIr+IemwIF/+Dvi8g0SYXI3e5Q2dgvI4/gxGDUiaopbLswhtcx5oil+wvpdQXhpcuweYJQ3frjjpC8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748365756; c=relaxed/simple; bh=n+3f+UHaZnbEXk/NY44C6UNL/OWCno4i627snpU+l8w=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TFcriKWqf2q0rQSg9H0hK8aKM2c0JLm1acabKBx4yzOoZo6iE7hEiiNjRSw0ylZ7pcZgm/vXGSzTIoP+wEdoxJ/KDJW3MSCh7wBSImkMA7wLnCrzHcA9MkcpvtjzfUIStdeJC0VbjyrqTdK2P+LXiJsMbbYWCTxyfJWduFxJD44= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=QY0SIWQf; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="QY0SIWQf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 76588C4CEED; Tue, 27 May 2025 17:09:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1748365755; bh=n+3f+UHaZnbEXk/NY44C6UNL/OWCno4i627snpU+l8w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QY0SIWQfmLYSy2QIhBPGpG9JMeDpbcyRXUZSMN3Gm6bvpKL4Y/7J2EvgDnsTFT98n dK9Dq/mtjiclHm7/QmOAwVdo3uv+rCxVgNHBgFRr+HVtW7vKiEt7GduIsSiYgcbEBW eUkWhCilmFAtetPi6uxRdH9yM1o9UOQXh5Ce1JyA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Petr Machata , Ido Schimmel , Eric Dumazet , Nikolay Aleksandrov , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.12 448/626] vxlan: Annotate FDB data races Date: Tue, 27 May 2025 18:25:41 +0200 Message-ID: <20250527162503.207229839@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250527162445.028718347@linuxfoundation.org> References: <20250527162445.028718347@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ 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 01f66760e1328..474faccf75fd9 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) @@ -1477,7 +1477,7 @@ 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); @@ -2825,7 +2825,7 @@ 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