From nobody Sun Oct 5 07:20:33 2025 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5B03145038; Wed, 6 Aug 2025 20:24:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754511859; cv=none; b=HtzVY++nJPxb9iN/D5+kYJamUl/YZDnhzwHYevncLD1KfWdl90F4I96WvDUEWTGKct8SEZZdB0/LA+rGPWM/S6eFreatXPCqeI9AY1Oh+fq6XyewTqhO8WCyKh1GfaT5GdkLFN6QPMlaZ5pVcaTQpEmYfq55/+BXtW+cSkmoWIg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754511859; c=relaxed/simple; bh=JVXedN0YzwVxacnO2vsgzYamqB/szo5YHrWDAURYETQ=; h=From:To:Cc:Subject:Date:Message-Id; b=srwJSsTCyTqwy2pLUQf8ZK9VQ+YpS6c46q80bUbrGR0YDoE78noz1VmB1xNCu0UQuEP5b7GVWJB8yHJmJCNZXD/T6yROjF3HSIxB1TKsq3ZD484vIXRFBzDWcnCvnsh8V0jT7xASTaF81H9mH1tZ+zq+K2e+55j5uKlwR7KVsPg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=bZ52YILX; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="bZ52YILX" Received: by linux.microsoft.com (Postfix, from userid 1006) id A4AD12030EAC; Wed, 6 Aug 2025 13:22:04 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com A4AD12030EAC DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1754511857; bh=KdToqvqVO3gNQw38sRKKvDdonhSef0op7Pd8H8o1HD0=; h=From:To:Cc:Subject:Date:From; b=bZ52YILXizZM8YzEFXgWo9spB8DOvnZGPzIKm0J50/h6Hz0Pifg55+PqH1JMoyms2 38ExPG74fEOB2dW6ADW8RZlisKZn2s36nmiXqzbceHVNAAqhAWKRlCO0hZpk0A7H8w yQDqCl3mNg+U7HhmQ+S3AefJMDRSVrGvN2oJgDDc= From: Haiyang Zhang To: linux-hyperv@vger.kernel.org, netdev@vger.kernel.org Cc: haiyangz@microsoft.com, kys@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, andrew+netdev@lunn.ch, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, davem@davemloft.net, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH net,v2] hv_netvsc: Fix panic during namespace deletion with VF Date: Wed, 6 Aug 2025 13:21:51 -0700 Message-Id: <1754511711-11188-1-git-send-email-haiyangz@linux.microsoft.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Haiyang Zhang The existing code move the VF NIC to new namespace when NETDEV_REGISTER is received on netvsc NIC. During deletion of the namespace, default_device_exit_batch() >> default_device_exit_net() is called. When netvsc NIC is moved back and registered to the default namespace, it automatically brings VF NIC back to the default namespace. This will cause the default_device_exit_net() >> for_each_netdev_safe loop unable to detect the list end, and hit NULL ptr: [ 231.449420] mana 7870:00:00.0 enP30832s1: Moved VF to namespace with: et= h0 [ 231.449656] BUG: kernel NULL pointer dereference, address: 0000000000000= 010 [ 231.450246] #PF: supervisor read access in kernel mode [ 231.450579] #PF: error_code(0x0000) - not-present page [ 231.450916] PGD 17b8a8067 P4D 0 [ 231.451163] Oops: Oops: 0000 [#1] SMP NOPTI [ 231.451450] CPU: 82 UID: 0 PID: 1394 Comm: kworker/u768:1 Not tainted 6.= 16.0-rc4+ #3 VOLUNTARY [ 231.452042] Hardware name: Microsoft Corporation Virtual Machine/Virtual= Machine, BIOS Hyper-V UEFI Release v4.1 11/21/2024 [ 231.452692] Workqueue: netns cleanup_net [ 231.452947] RIP: 0010:default_device_exit_batch+0x16c/0x3f0 [ 231.453326] Code: c0 0c f5 b3 e8 d5 db fe ff 48 85 c0 74 15 48 c7 c2 f8 = fd ca b2 be 10 00 00 00 48 8d 7d c0 e8 7b 77 25 00 49 8b 86 28 01 00 00 <48= > 8b 50 10 4c 8b 2a 4c 8d 62 f0 49 83 ed 10 4c 39 e0 0f 84 d6 00 [ 231.454294] RSP: 0018:ff75fc7c9bf9fd00 EFLAGS: 00010246 [ 231.454610] RAX: 0000000000000000 RBX: 0000000000000002 RCX: 61c8864680b= 583eb [ 231.455094] RDX: ff1fa9f71462d800 RSI: ff75fc7c9bf9fd38 RDI: 00000000307= 66564 [ 231.455686] RBP: ff75fc7c9bf9fd78 R08: 0000000000000000 R09: 00000000000= 00000 [ 231.456126] R10: 0000000000000001 R11: 0000000000000004 R12: ff1fa9f7008= 8e340 [ 231.456621] R13: ff1fa9f70088e340 R14: ffffffffb3f50c20 R15: ff1fa9f7103= e6340 [ 231.457161] FS: 0000000000000000(0000) GS:ff1faa6783a08000(0000) knlGS:= 0000000000000000 [ 231.457707] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 231.458031] CR2: 0000000000000010 CR3: 0000000179ab2006 CR4: 0000000000b= 73ef0 [ 231.458434] Call Trace: [ 231.458600] [ 231.458777] ops_undo_list+0x100/0x220 [ 231.459015] cleanup_net+0x1b8/0x300 [ 231.459285] process_one_work+0x184/0x340 To fix it, move the ns change to a workqueue, and take rtnl_lock to avoid changing the netdev list when default_device_exit_net() is using it. Cc: stable@vger.kernel.org Fixes: 4c262801ea60 ("hv_netvsc: Fix VF namespace also in synthetic NIC NET= DEV_REGISTER event") Signed-off-by: Haiyang Zhang --- v2: Moved the ns change to a workqueue as suggested by Jakub Kicinski. --- drivers/net/hyperv/hyperv_net.h | 3 +++ drivers/net/hyperv/netvsc_drv.c | 29 ++++++++++++++++++++++++++++- 2 files changed, 31 insertions(+), 1 deletion(-) diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_ne= t.h index cb6f5482d203..7397c693f984 100644 --- a/drivers/net/hyperv/hyperv_net.h +++ b/drivers/net/hyperv/hyperv_net.h @@ -1061,6 +1061,7 @@ struct net_device_context { struct net_device __rcu *vf_netdev; struct netvsc_vf_pcpu_stats __percpu *vf_stats; struct delayed_work vf_takeover; + struct delayed_work vfns_work; =20 /* 1: allocated, serial number is valid. 0: not allocated */ u32 vf_alloc; @@ -1075,6 +1076,8 @@ struct net_device_context { struct netvsc_device_info *saved_netvsc_dev_info; }; =20 +void netvsc_vfns_work(struct work_struct *w); + /* Azure hosts don't support non-TCP port numbers in hashing for fragmented * packets. We can use ethtool to change UDP hash level when necessary. */ diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_dr= v.c index f44753756358..39c892e46cb0 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -2522,6 +2522,7 @@ static int netvsc_probe(struct hv_device *dev, spin_lock_init(&net_device_ctx->lock); INIT_LIST_HEAD(&net_device_ctx->reconfig_events); INIT_DELAYED_WORK(&net_device_ctx->vf_takeover, netvsc_vf_setup); + INIT_DELAYED_WORK(&net_device_ctx->vfns_work, netvsc_vfns_work); =20 net_device_ctx->vf_stats =3D netdev_alloc_pcpu_stats(struct netvsc_vf_pcpu_stats); @@ -2666,6 +2667,8 @@ static void netvsc_remove(struct hv_device *dev) cancel_delayed_work_sync(&ndev_ctx->dwork); =20 rtnl_lock(); + cancel_delayed_work_sync(&ndev_ctx->vfns_work); + nvdev =3D rtnl_dereference(ndev_ctx->nvdev); if (nvdev) { cancel_work_sync(&nvdev->subchan_work); @@ -2707,6 +2710,7 @@ static int netvsc_suspend(struct hv_device *dev) cancel_delayed_work_sync(&ndev_ctx->dwork); =20 rtnl_lock(); + cancel_delayed_work_sync(&ndev_ctx->vfns_work); =20 nvdev =3D rtnl_dereference(ndev_ctx->nvdev); if (nvdev =3D=3D NULL) { @@ -2800,6 +2804,27 @@ static void netvsc_event_set_vf_ns(struct net_device= *ndev) } } =20 +void netvsc_vfns_work(struct work_struct *w) +{ + struct net_device_context *ndev_ctx =3D + container_of(w, struct net_device_context, vfns_work.work); + struct net_device *ndev; + + if (!rtnl_trylock()) { + schedule_delayed_work(&ndev_ctx->vfns_work, 1); + return; + } + + ndev =3D hv_get_drvdata(ndev_ctx->device_ctx); + if (!ndev) + goto out; + + netvsc_event_set_vf_ns(ndev); + +out: + rtnl_unlock(); +} + /* * On Hyper-V, every VF interface is matched with a corresponding * synthetic interface. The synthetic interface is presented first @@ -2810,10 +2835,12 @@ static int netvsc_netdev_event(struct notifier_bloc= k *this, unsigned long event, void *ptr) { struct net_device *event_dev =3D netdev_notifier_info_to_dev(ptr); + struct net_device_context *ndev_ctx; int ret =3D 0; =20 if (event_dev->netdev_ops =3D=3D &device_ops && event =3D=3D NETDEV_REGIS= TER) { - netvsc_event_set_vf_ns(event_dev); + ndev_ctx =3D netdev_priv(event_dev); + schedule_delayed_work(&ndev_ctx->vfns_work, 0); return NOTIFY_DONE; } =20 --=20 2.34.1