From nobody Sun Dec 14 12:06:26 2025 Received: from mail-pf1-f179.google.com (mail-pf1-f179.google.com [209.85.210.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3E3B527718; Thu, 22 May 2025 03:11:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.179 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747883494; cv=none; b=WLEG83H9YRj7hByMrztxkRjOJhychp8yB24h1vnj7sftquTHDNutTTDatabhU+SM128vzvppOT/EheonIMmBuTz6MyjeEvX/SZMWhufAyBaVj3U0i2GaHk2dlWsiLpEKqZd2zBOZukmc/fRlNy1/XD/YA7Ny6WkH40TS95g78Wg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747883494; c=relaxed/simple; bh=IPYn8fz9zcaLbQa6XS0icpIQHNwzuXngs2jCr56c5a8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Z0k8UjTfNT2fXxqF5NrzVtmRtnzodL12esUPzg5UQyR7l5HSlzfKxD7D483OYCUq5z/xfhHqxPEzyrj5GeHKTzys0J6tO0OhkzA6JnjEEytC8+k0qww8+aFi6XjhXFBR3jMH5LDb1PlH2wyZ5Gjvyg6KcPQgDEqQsC2BBpjFKKk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=fphwMoIx; arc=none smtp.client-ip=209.85.210.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="fphwMoIx" Received: by mail-pf1-f179.google.com with SMTP id d2e1a72fcca58-742c2ed0fe1so4796383b3a.1; Wed, 21 May 2025 20:11:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1747883490; x=1748488290; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=w2h1eS/LzljS1IIkostr5pLzZhBsy848oiMCgLs6Xg0=; b=fphwMoIx46qjrqKzTUlfF0Wl0/K3dH47qqvnkcDx3lV7VLfwlzdTyseGDSw4lpJzbM Uh4cFWiTESP5T1qCUnEQec8QcH6lH/4KLCvOJlJUKLLERVx5z652yK1cRDMzHlx43pya I2g/qhbqdpfqUbTOYhO2EWYLt3jlP1ec0G65tK6S88R9zvEPtQxHLnVsjFcBjfjd92Fx KG5S+dHtDAbVkufrOTFhLbrDKvgX9Fc7BjXGxGdehpjhpNvfsvQzJtPNn7QBIRChauxG UZSBP7RyJRZYticRnDm/A2DC9HCYcfTq7evLzRl2ZhuCgPgQXD8ajplwreOdErjSie8p 1dCQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1747883490; x=1748488290; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=w2h1eS/LzljS1IIkostr5pLzZhBsy848oiMCgLs6Xg0=; b=Qtv0J1IW4EpEiMEHmuNeorAs3OP4goGMTTwSMyXQ+hoHZ7yjysN8BbMlj3YUoYC8Ln 9U5dKD+O0GOUG7G0BtECReXDRZCmq42VM5YTuAK5vW5nLvyQH12kyHMXVMRmy7kHpzQN ZF4eoaLprSwrqow6OiMSWks2J/JG7gtgOWJPO0Mdt+hpCokrbMkKvBm8rpF5cujXz0Yc C+ff8EHaXTSewnqWjtbMVBXeRU5CGiv/vBMi5Od2h8tHTAx2HQSfWkXHxOnbvPIkEGCL i29khUfYK71SwQidxXJ/dLfvpvDCwV4Uu5iPteikXKUQtsoRobs69xGP6vX7QQ3SlRXC sH1A== X-Forwarded-Encrypted: i=1; AJvYcCVfIfWosW01K3QMWSqZqYruJFfu8+NWOeGMPPyw4QUgO9qd+q6Ov5SanNbjMiMDI/wBqRemWw5uX/yVBKc=@vger.kernel.org X-Gm-Message-State: AOJu0Yzx3weyRaorl8+z7+elT+lsiM0rsyKS1FaiubzS7aIsHMKstPW5 AM/bXuv6jJvBx3Fv6k/HQIdxgoC4Vj9pzhgGpME+spMyKqmIIN9TLJhP5bZ5 X-Gm-Gg: ASbGnctCKnBpo7X9KZ2SRjEyLrageuTkvXSpFpna54cBHr2mJDruEVvgMqIbmz4CRFn s0qIHTmI6/SZNLyJWdfxgImelujyC6X75t0mvTLGeFy0INMyC9RrH1hgQDWxTGBXhZtlg9AK0KH W2xRu71aD5AbujuqDsOodWbsqeFixxBS71MUeuT8mZhmY6bV7alliHhgMqIDYxlI7skv3yDishs dRhCwMC01Gr0OyNuHQfQIJ6qEgwC5wvSVIed0PHNLJqb9nVWUlR83NxUu9mDtdTEz6j+3kTR2xF 7U3hxtsXrKp7W2Gk8DA0Il4k/oe7xczCSaa1YvfheMD64TGmX+X/wyjb+J1Wnoj6R5USmgxHZzU ExbU/+PQHd9Va X-Google-Smtp-Source: AGHT+IGniznh0ts9NxFH5+t9kJd249DOK+nfbCXQCEmCmvkI5lLK6lXs4GEDFzVngyLAHgRCQ3e+Rw== X-Received: by 2002:a05:6a21:502:b0:203:ca66:e30 with SMTP id adf61e73a8af0-216219edf88mr37148896637.37.1747883490479; Wed, 21 May 2025 20:11:30 -0700 (PDT) Received: from localhost (c-73-158-218-242.hsd1.ca.comcast.net. [73.158.218.242]) by smtp.gmail.com with UTF8SMTPSA id d2e1a72fcca58-742a97395basm10351194b3a.76.2025.05.21.20.11.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 May 2025 20:11:30 -0700 (PDT) From: Stanislav Fomichev To: netdev@vger.kernel.org Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, willemdebruijn.kernel@gmail.com, horms@kernel.org, stfomichev@gmail.com, linux-kernel@vger.kernel.org, syzbot+b191b5ccad8d7a986286@syzkaller.appspotmail.com Subject: [PATCH net v2] af_packet: move notifier's packet_dev_mc out of rcu critical section Date: Wed, 21 May 2025 20:11:28 -0700 Message-ID: <20250522031129.3247266-1-stfomichev@gmail.com> X-Mailer: git-send-email 2.49.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Syzkaller reports the following issue: BUG: sleeping function called from invalid context at kernel/locking/mutex= .c:578 __mutex_lock+0x106/0xe80 kernel/locking/mutex.c:746 team_change_rx_flags+0x38/0x220 drivers/net/team/team_core.c:1781 dev_change_rx_flags net/core/dev.c:9145 [inline] __dev_set_promiscuity+0x3f8/0x590 net/core/dev.c:9189 netif_set_promiscuity+0x50/0xe0 net/core/dev.c:9201 dev_set_promiscuity+0x126/0x260 net/core/dev_api.c:286 packet_dev_mc net/p= acket/af_packet.c:3698 [inline] packet_dev_mclist_delete net/packet/af_packet.c:3722 [inline] packet_notifier+0x292/0xa60 net/packet/af_packet.c:4247 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85 call_netdevice_notifiers_extack net/core/dev.c:2214 [inline] call_netdevice_notifiers net/core/dev.c:2228 [inline] unregister_netdevice_many_notify+0x15d8/0x2330 net/core/dev.c:11972 rtnl_delete_link net/core/rtnetlink.c:3522 [inline] rtnl_dellink+0x488/0x710 net/core/rtnetlink.c:3564 rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6955 netlink_rcv_skb+0x219/0x490 net/netlink/af_netlink.c:2534 Calling `PACKET_ADD_MEMBERSHIP` on an ops-locked device can trigger the `NETDEV_UNREGISTER` notifier, which may require disabling promiscuous and/or allmulti mode. Both of these operations require acquiring the netdev instance lock. Move the call to `packet_dev_mc` outside of the RCU critical section. The `mclist` modifications (add, del, flush, unregister) are protected by the RTNL, not the RCU. The RCU only protects the `sklist` and its associated `sks`. The delayed operation on the `mclist` entry remains within the RTNL. Reported-by: syzbot+b191b5ccad8d7a986286@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3Db191b5ccad8d7a986286 Fixes: ad7c7b2172c3 ("net: hold netdev instance lock during sysfs operation= s") Signed-off-by: Stanislav Fomichev Reviewed-by: Willem de Bruijn --- v2: revise commit message (Willem & Jakub) and add INIT_LIST_HEAD (Willem) --- net/packet/af_packet.c | 21 ++++++++++++++++----- net/packet/internal.h | 1 + 2 files changed, 17 insertions(+), 5 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index d4dba06297c3..20be2c47cf41 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3713,15 +3713,15 @@ static int packet_dev_mc(struct net_device *dev, st= ruct packet_mclist *i, } =20 static void packet_dev_mclist_delete(struct net_device *dev, - struct packet_mclist **mlp) + struct packet_mclist **mlp, + struct list_head *list) { struct packet_mclist *ml; =20 while ((ml =3D *mlp) !=3D NULL) { if (ml->ifindex =3D=3D dev->ifindex) { - packet_dev_mc(dev, ml, -1); + list_add(&ml->remove_list, list); *mlp =3D ml->next; - kfree(ml); } else mlp =3D &ml->next; } @@ -3769,6 +3769,7 @@ static int packet_mc_add(struct sock *sk, struct pack= et_mreq_max *mreq) memcpy(i->addr, mreq->mr_address, i->alen); memset(i->addr + i->alen, 0, sizeof(i->addr) - i->alen); i->count =3D 1; + INIT_LIST_HEAD(&i->remove_list); i->next =3D po->mclist; po->mclist =3D i; err =3D packet_dev_mc(dev, i, 1); @@ -4233,9 +4234,11 @@ static int packet_getsockopt(struct socket *sock, in= t level, int optname, static int packet_notifier(struct notifier_block *this, unsigned long msg, void *ptr) { - struct sock *sk; struct net_device *dev =3D netdev_notifier_info_to_dev(ptr); struct net *net =3D dev_net(dev); + struct packet_mclist *ml, *tmp; + LIST_HEAD(mclist); + struct sock *sk; =20 rcu_read_lock(); sk_for_each_rcu(sk, &net->packet.sklist) { @@ -4244,7 +4247,8 @@ static int packet_notifier(struct notifier_block *thi= s, switch (msg) { case NETDEV_UNREGISTER: if (po->mclist) - packet_dev_mclist_delete(dev, &po->mclist); + packet_dev_mclist_delete(dev, &po->mclist, + &mclist); fallthrough; =20 case NETDEV_DOWN: @@ -4277,6 +4281,13 @@ static int packet_notifier(struct notifier_block *th= is, } } rcu_read_unlock(); + + /* packet_dev_mc might grab instance locks so can't run under rcu */ + list_for_each_entry_safe(ml, tmp, &mclist, remove_list) { + packet_dev_mc(dev, ml, -1); + kfree(ml); + } + return NOTIFY_DONE; } =20 diff --git a/net/packet/internal.h b/net/packet/internal.h index d5d70712007a..1e743d0316fd 100644 --- a/net/packet/internal.h +++ b/net/packet/internal.h @@ -11,6 +11,7 @@ struct packet_mclist { unsigned short type; unsigned short alen; unsigned char addr[MAX_ADDR_LEN]; + struct list_head remove_list; }; =20 /* kbdq - kernel block descriptor queue */ --=20 2.49.0