From patchwork Thu Mar 13 10:04:07 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stanislav Fomichev X-Patchwork-Id: 14014623 X-Patchwork-Delegate: kuba@kernel.org Received: from mail-pl1-f170.google.com (mail-pl1-f170.google.com [209.85.214.170]) (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 ABE4E13B5A0; Thu, 13 Mar 2025 10:04:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.170 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741860251; cv=none; b=ezJq4GVqy/ICSdQn2NEqQOhH6Ri/IbsSiB91UtxlvL2Ek1t/NFK/opKhl4wiGkwbyxNqNGnNBTC3KrYOrpqZ9y6L3xffqPD4kYu7iyGYxUOz/jo4EF5mxG5hEC5yRAWgFUrPcmwGtVvyZKqvJBPmQPIacQMBZMxaWLhi+SXqzLo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741860251; c=relaxed/simple; bh=1d9rwvR5saCp0EdhYztcjIdDfwg5pjT3HmajtsxKKTc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Z7Qy3CrjMjspzipFpJ2j4OOCzowzaza24ucmCqSBU6x1KiQWMCDdBmU/usEMZAKAIZG8xXXWtaoIMRKUJXE0jtiVx+4jnDWsAOEJN8uV1p0aQ5aOqaM7cR2cLbzRxBeUGksYJqypEbyLezxi9glrRDojDd1sgdc+PguXUNTWUbk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fomichev.me; spf=pass smtp.mailfrom=gmail.com; arc=none smtp.client-ip=209.85.214.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=fomichev.me Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pl1-f170.google.com with SMTP id d9443c01a7336-223959039f4so13765045ad.3; Thu, 13 Mar 2025 03:04:09 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1741860248; x=1742465048; 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=ZTpDb7E7Kgg1mQRDqCTRFcTgplYc3DjbNW4+KhK/wVU=; b=QLLQJyvwr2VRQJ/gcLojzFICuB0zuaawowtTEaD6cza03dF5X4z1ZvpoCts4OxaAtv qKg1JPwnLCGQyPL2Sgxpm5tmCqoOafdAchqHbogzyzrslgkwKJnU9rYgXQQzHaMoypdP GCSr694lST5WOrN7CxyCEn2BSBIi6lIy299dKCvsNJ0dMnt59ATsC0IPHMtfkglrFzDO UWTw7ErScVlddP2pNioKlgYJ2SAGhUVyt+GmD18i9HNSsAKHdMu6qwHZezcDw/bPCKZc AtacE+vr/MNbqWIzpcmejJ9wh1DVA6EfiRNNOELVmeAmtXcqU37zAJwUwXXSacKwvXA5 9jyQ== X-Forwarded-Encrypted: i=1; AJvYcCXEZudVDA+gr/BHrnynkdczaN5kQE2PvONfvmNPChsgU/givzY/QlQd8BDssxnJscJgJ4nq276qlbFYo44=@vger.kernel.org X-Gm-Message-State: AOJu0YwzK4sJopXzE/GcbdeEDOUycIw2krR5mjP4+uZoCeT2wIDi3WS9 pbiwwRmAnbVYZYzPeaZ+cBAQOclVvGeqYXdHjXbPNXVXbK6lGZzfD151duFrXQ== X-Gm-Gg: ASbGncvzBay2D7hSqeIAeAR6vnLxiuqFTQjlaJ2TrKz4FrSC3a2T2aXcq4FvIgjzhk4 Q2VxdpwiX2/C6aKOme9KOzYhojg43MmRi9IhCnJ29DSfuo+pY9NNtFDRckRybaNdRp9yOtkhBFR Y0PDwrwD8yzCsK1r/m43YSlCNkTKAZWMU8l1BJylAbAqdxF8W5ar8MAm4hFQaLXHRuNBZ5ROPxR IXqrRzfDWVxJ9Sz6uj8XisYvc2ebMSvXAd90SAWJsVKvFAijDhrd/g7lbll56tE4qTKCOcJzvDn 6XK1dxJTvAJkqKpFZxfhrTeN8rjIGKEaX7wVIMsaV0Tt X-Google-Smtp-Source: AGHT+IFX6/pa4VhGBivbCC3CtJNwH1YfTlzwX4CCD5m8Y0Zl+Ld8fkpWuWGDaqr+P+mpvgxyketlVQ== X-Received: by 2002:a05:6a00:3981:b0:736:a7e3:d4ab with SMTP id d2e1a72fcca58-736aa9d32bemr30744617b3a.5.1741860248431; Thu, 13 Mar 2025 03:04:08 -0700 (PDT) Received: from localhost ([2601:646:9e00:f56e:2844:3d8f:bf3e:12cc]) by smtp.gmail.com with UTF8SMTPSA id d2e1a72fcca58-73711694b72sm983524b3a.133.2025.03.13.03.04.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Mar 2025 03:04:07 -0700 (PDT) From: Stanislav Fomichev To: netdev@vger.kernel.org Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, linux-kernel@vger.kernel.org, jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us, horms@kernel.org, sdf@fomichev.me Subject: [PATCH net-next] net: don't relock netdev when on qdisc_create replay Date: Thu, 13 Mar 2025 03:04:07 -0700 Message-ID: <20250313100407.2285897-1-sdf@fomichev.me> X-Mailer: git-send-email 2.48.1 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org Eric reports that by the time we call netdev_lock_ops after rtnl_unlock/rtnl_lock, the dev might point to an invalid device. Don't relock the device after request_module and don't try to unlock it in the caller (tc_modify_qdisc) in case of replay. Fixes: a0527ee2df3f ("net: hold netdev instance lock during qdisc ndo_setup_tc") Reported-by: Eric Dumazet Link: https://lore.kernel.org/netdev/20250305163732.2766420-1-sdf@fomichev.me/T/#me8dfd778ea4c4463acab55644e3f9836bc608771 Signed-off-by: Stanislav Fomichev --- net/sched/sch_api.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c index abace7665cfe..f1ec6ec0cf05 100644 --- a/net/sched/sch_api.c +++ b/net/sched/sch_api.c @@ -1278,13 +1278,14 @@ static struct Qdisc *qdisc_create(struct net_device *dev, * tell the caller to replay the request. We * indicate this using -EAGAIN. * We replay the request because the device may - * go away in the mean time. + * go away in the mean time. Note that we also + * don't relock the device because it might + * be gone at this point. */ netdev_unlock_ops(dev); rtnl_unlock(); request_module(NET_SCH_ALIAS_PREFIX "%s", name); rtnl_lock(); - netdev_lock_ops(dev); ops = qdisc_lookup_ops(kind); if (ops != NULL) { /* We will try again qdisc_lookup_ops, @@ -1837,9 +1838,10 @@ static int tc_modify_qdisc(struct sk_buff *skb, struct nlmsghdr *n, replay = false; netdev_lock_ops(dev); err = __tc_modify_qdisc(skb, n, extack, dev, tca, tcm, &replay); - netdev_unlock_ops(dev); + /* __tc_modify_qdisc returns with unlocked dev in case of replay */ if (replay) goto replay; + netdev_unlock_ops(dev); return err; }