From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f49.google.com (mail-wm1-f49.google.com [209.85.128.49]) (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 699843DA5B1 for ; Fri, 29 May 2026 13:59:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.49 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780063191; cv=none; b=Ls4PjmJbnu08vHlIOoG95uuz9Zb7N4+PAvLNhGntBM3V+P+mBtDnU3eGd/9YohN/5invCBP36lAeQMBexI9stWSl3sssWITgys+Tv2wuJ6qYAahSEifkjlzQXVX2a6Wf/sBGgl2qVZGYPUfC1l1Z1zkJHdSg7haNfTpSAn9W2hs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780063191; c=relaxed/simple; bh=KYVlRd1aquTP3bMRf1yqpg8Q8zkl/MFBUrtYhsbb0b8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=YnwN2WvMnSArViqervT1P+myB6VQHSncjwVo6XPDg/cD272BXLf/mb/AmTaB1JQo1wAbmHzBqevhDYyXjtJQ+ywQLIeVdw4YCHN6LlblmzFCxqVRPEBo0il8yPBLPM/FTf9MfgNgnS3SBOPyoRqzQ+xtqQArgHxfBd7thF3Sgu4= 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=S5CbpKTK; arc=none smtp.client-ip=209.85.128.49 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="S5CbpKTK" Received: by mail-wm1-f49.google.com with SMTP id 5b1f17b1804b1-490227b682cso7168225e9.3 for ; Fri, 29 May 2026 06:59:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1780063186; x=1780667986; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=n5MBJ+x5az2tq5WcU9vWA3tYOf7P2ieIA9xjXOxXWIs=; b=S5CbpKTKucfo8HNm5fURinWau6BF7wBsryw7Hc4eXGO4cDX5ZYYRqvGMo6yM1UdYSN yGWv9dZ37cpre8Xo+xvTr3IfLMGCOw4Z8ZvL0fL4S+fj9re8EogSqBjnkKReV6IpCUtM G+snvZz8HCpGrfqzL9Q1QYptrJPb+5XBzM9UonTuRnUfn8P9biR/ayP7FWcHZsW0WxIO XRQCGVvK1EedoynXe/lK9p7JnUI0Y/dSAra9R4MQhBX+wEMvS3kw/VTWsy+FYQzs7E89 jeM6SVey1P+8WcYf2kAX2kAjh2J67SXkbVSka35C4aku1qRd94VCzjLinlnS94Ujar35 78/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780063186; x=1780667986; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=n5MBJ+x5az2tq5WcU9vWA3tYOf7P2ieIA9xjXOxXWIs=; b=ES4HG3lZBBN9CbEG+L+5Ssv7TwnJa6MRPLT5NcGLGQnWmveItKGf2NIWGLLpZf1pqk eC0Tz2ST1a4etVnDefDrL4JzcPkC0re2kAvFllrX/Vd/5e/nh65bYwZbYKP3wB7ssh2b CubUAe0hPkfeiIcnPtVClLOT06R70VihxPgEiAqqm8svbaOxvnJsTMA94TISZuDK0NAo gzqxy+sSRFEnnTymKaiqhMOMZX72eaDaJ+9oI+js2YxWePHf/oG0jxIIcCM2n3RDnpmQ NOTk5syIR2DXPlvSGT9ekfSICItE3Tgi6FCvSuFSgnvgyRNSugBnbq8SIxVxpq8BT8uJ cxNA== X-Forwarded-Encrypted: i=1; AFNElJ+OyPhiYL/g6thtl1qeqGltmVG+33AXjl4O0Ry7+7XkktQwcDPKPhceI10RpIIym+GnpovcDmPU/NBAZuk=@vger.kernel.org X-Gm-Message-State: AOJu0YxW0v4FGsocAiwAPqcCAnIiF9frT3yaOZihB+Livzftso+lGs3b PbmUbiETp9JQl3tgPmdcB0oNBhM5mq+BA4+82z5yDahRVnVt5bQv21UG X-Gm-Gg: Acq92OGBNmGQ4fC3bwRV/ka4+y6yvrGgmjpLk05LE8hxHWYgXPNva5AJWJ0ofJKg8Mj GRk57fTYPk6xrTRy+ykrHVh3YCl2WnDOgX84mU5NauD+uqqWXgOVj510wM6dTWAJDrEtSH4SCvL VUzeh59rjBDjRH8i8x5QI2yPrWlcx4+3CNHa9Xj6DuVBO4hTE4Xx4JHqAGB3ONd8S6KbH6Eklsq Me/5TrEaf1rG8jbnjNXriI6aXCwNBBLoFYbfS3ltgR8r/bUfgwoL4U8KMnrG2E7WeKhFcOuVOuT QTX8De0YTlKzXc3lr72TYw3o9uVa0fspYn8j+s8TCP7xhUmltUHImMI6cNLPypdl6iwryYaC0Fv UcXW140Ni/nqWkAEOegupuKlQKufVolGuOITwd5YvFljamXODKQmt+TXuKm2ei2u2UFUrMMrxUM A4q7NAZyjsVc0unsE5PxJ/3ly2pV1Pz7BgpTkhWvbvcixE0PHJGbveP3VntC0loCYKWU4IeYzws mvRQe3z6U3m716ieBf9FxNon55t/ZKrgA== X-Received: by 2002:a05:600c:4f53:b0:489:1fa8:b895 with SMTP id 5b1f17b1804b1-4909c0845ccmr21882065e9.2.1780063185440; Fri, 29 May 2026 06:59:45 -0700 (PDT) Received: from ?IPV6:2a02:aa16:1105:8100:157a:cab0:dc27:cd03? ([2a02:aa16:1105:8100:157a:cab0:dc27:cd03]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4909c0c39b0sm25645315e9.2.2026.05.29.06.59.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 29 May 2026 06:59:45 -0700 (PDT) Message-ID: Date: Fri, 29 May 2026 15:59:44 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] netdevsim: fib: fix use-after-free of FIB data via debugfs To: Ido Schimmel Cc: Jakub Kicinski , Andrew Lunn , "David S . Miller" , Eric Dumazet , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260526160910.1614609-1-yzjaurora@gmail.com> <20260527083214.GA444725@shredder> Content-Language: en-US From: Zijing yin In-Reply-To: <20260527083214.GA444725@shredder> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Thanks so much for the feedback! I have sent the revised patch accordingly: https://lore.kernel.org/netdev/20260529135718.1804031-1-yzjaurora@gmail.com/T/#u Hope you have a nice weekend! On 27.05.2026 10:32, Ido Schimmel wrote: > On Tue, May 26, 2026 at 09:09:08AM -0700, Zijing Yin wrote: >> @@ -1600,6 +1597,16 @@ struct nsim_fib_data *nsim_fib_create(struct devlink *devlink, >> goto err_nexthop_nb_unregister; >> } >> >> + /* Publish the debugfs interface only after every data structure it >> + * operates on has been initialized. The files reference this >> + * nsim_fib_data (e.g. "nexthop_bucket_activity" looks up >> + * data->nexthop_ht), so a concurrent debugfs access must never be able >> + * to observe a half-constructed instance. >> + */ >> + err = nsim_fib_debugfs_init(data, nsim_dev); >> + if (err) >> + goto err_fib_notifier_unregister; >> + >> devl_resource_occ_get_register(devlink, >> NSIM_RESOURCE_IPV4_FIB, >> nsim_fib_ipv4_resource_occ_get, >> @@ -1622,6 +1629,8 @@ struct nsim_fib_data *nsim_fib_create(struct devlink *devlink, >> data); >> return data; >> >> +err_fib_notifier_unregister: >> + unregister_fib_notifier(devlink_net(devlink), &data->fib_nb); >> err_nexthop_nb_unregister: >> unregister_nexthop_notifier(devlink_net(devlink), &data->nexthop_nb); >> err_rhashtable_fib_destroy: >> @@ -1633,16 +1642,23 @@ struct nsim_fib_data *nsim_fib_create(struct devlink *devlink, >> rhashtable_free_and_destroy(&data->nexthop_ht, nsim_nexthop_free, >> data); >> mutex_destroy(&data->fib_lock); >> -err_debugfs_exit: >> +err_nh_lock_destroy: >> mutex_destroy(&data->nh_lock); >> - nsim_fib_debugfs_exit(data); >> -err_data_free: >> kfree(data); >> return ERR_PTR(err); >> } >> >> void nsim_fib_destroy(struct devlink *devlink, struct nsim_fib_data *data) >> { >> + /* Tear down the debugfs files before freeing the data structures they >> + * operate on. debugfs_remove_recursive() waits for any in-flight file >> + * operation (e.g. a write to "fib/nexthop_bucket_activity", which looks >> + * up data->nexthop_ht) to finish and prevents new ones from starting, >> + * so the rhashtables are not freed while a concurrent accessor still >> + * dereferences them. >> + */ >> + nsim_fib_debugfs_exit(data); > > Thanks for the patch. Let's try to keep both functions symmetric: > > Call nsim_fib_debugfs_exit() just before unregister_fib_notifier(). > > Also, I would drop the comments. > >> + >> devl_resource_occ_get_unregister(devlink, >> NSIM_RESOURCE_NEXTHOPS); >> devl_resource_occ_get_unregister(devlink, >> @@ -1665,6 +1681,5 @@ void nsim_fib_destroy(struct devlink *devlink, struct nsim_fib_data *data) >> WARN_ON_ONCE(!list_empty(&data->fib_rt_list)); >> mutex_destroy(&data->fib_lock); >> mutex_destroy(&data->nh_lock); >> - nsim_fib_debugfs_exit(data); >> kfree(data); >> } >> -- >> 2.43.0 >>