From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lj1-f170.google.com (mail-lj1-f170.google.com [209.85.208.170]) (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 68558182CC for ; Sat, 4 May 2024 11:04:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714820675; cv=none; b=rIhTwkxtxd3TKbrGiW1FLe8LG1UsV6iCWzlFQ2cb7femxCt1ouauy/id1fLItERL+P4wSYWiIIwi0gdJbKmKNQszh/KeHM2xEXkkE2gOGMP3TvuxdTDiCx02S19dI4fdkKB34Wb2e8ZcxN5T1d06SLSfL7+xrk2B5IZ4zGc+D1g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714820675; c=relaxed/simple; bh=oESbJrzd3NodVfpRoKiTo6HVR3uCwGr/hSqHg54pang=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nT6WxPYyLJAt+spwECG84gQJmHPLYIC5DDgYxAbne4Eb/GqlEslV0rXbMNiQm4ZilodSYPmIVDi9XQi91tfhZcxFzkznbVvDzHzo2D4q2INm0ZCOkvnQiRDIYS2RpCJj6bSRtNatK3hUURF/enxLvqPNEngU256gXcVVSswsqtY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org; spf=pass smtp.mailfrom=linaro.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b=NdSEcuHB; arc=none smtp.client-ip=209.85.208.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linaro.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="NdSEcuHB" Received: by mail-lj1-f170.google.com with SMTP id 38308e7fff4ca-2e20f2db068so4980801fa.2 for ; Sat, 04 May 2024 04:04:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1714820672; x=1715425472; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=QqIw4+jSQ5b87qweNz9VaPv59kaDSpMsRWOBQ8BsgAg=; b=NdSEcuHBHsnxVuuIuxZq58ivVP8dULucAlMREwUXNdeXdLpQsRMAUtmCwqdbGWNH9y ik+LYWye3m09isZWNiRtP1/RWGsqOruQK6PAkBhmGusQL7Ak+ZeChkF/3TmSszp4ieoj 3D7yQwQdGjL26cpGHqaMs2KyHM0UvSGZ9G0IYSOG4u4P7RDaRgOgzxbcbvnD4Wm3opVB P/PerrDOn8PRdzpATmxrB6uNU9PmjVTT+mlR4bQMtRYPYlQH/NZOBOcisOftf9xGvK89 AgOpcQ8tvVVZS5xn2fEmzWyAw5iDERf2DFl8QXgr+R1bxW0VGEvl3g0xPFOfsiWnwChc uvtg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1714820672; x=1715425472; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=QqIw4+jSQ5b87qweNz9VaPv59kaDSpMsRWOBQ8BsgAg=; b=TTsakwekZh+T6Qx3YEOq40Ydy+iFS9TaRcId+qzfZKGP2VskWulXbutb+70PeFyj41 4oJvEifKMFHza3rSYpdAULXiG1yP76KTe2xq8m71V8UH9z268k2/WIHmVc/Y25krXFTj 7w7zgIID2kUDA9NwmVXamtSCsnRXwrN25UafbcGUMm2mqgVgbrds3hilAugoXoJZTy4s iFRz1KRcXdju4pk+zA5NufQ9l7/Z6paXxgFs7bn6cqT5wNllNwFyr+dmROzPY6CdTwD+ 0shMsd3TxYlCMAti2t/XH6LLCpltzsmQvQBEZT1dzkBQDtGVh1kXS2kU3y6YmXLRMOtB Vxeg== X-Forwarded-Encrypted: i=1; AJvYcCV0kuqllcxkGco51alU1HWGDVb+vw4GfzwdS2zuw3FrO3r9T/jhN41T0R8JXxVNpqhlT7+xrXEIRYzMZ9OtCSNEQPBRiUDl X-Gm-Message-State: AOJu0Yyg+s/YA6+Q3qRnZZmNag1R9YMHzehB+HgxJFjy+tiPWBWICRAR HcoPmDJ3UhDP6cIrZvzwQfLzZIeo/pTmn1F9yue7wOsowYNNKTcti3NQjVZ/2p8DrO1aA+df3Ua s X-Google-Smtp-Source: AGHT+IEVLFaJ2xohkXrGS/+Gw9GuM+CyPwMFte2/sMkc5UfIYuU5HWmYlOdvr36TRiKJGIRWgrjzcQ== X-Received: by 2002:a2e:3612:0:b0:2d9:f00c:d2d5 with SMTP id d18-20020a2e3612000000b002d9f00cd2d5mr3018955lja.46.1714820671226; Sat, 04 May 2024 04:04:31 -0700 (PDT) Received: from localhost ([102.222.70.76]) by smtp.gmail.com with ESMTPSA id k6-20020a05600c478600b004185be4baefsm9006237wmo.0.2024.05.04.04.04.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 04 May 2024 04:04:30 -0700 (PDT) Date: Sat, 4 May 2024 14:04:26 +0300 From: Dan Carpenter To: Duoming Zhou Cc: linux-hams@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, pabeni@redhat.com, kuba@kernel.org, edumazet@google.com, davem@davemloft.net, jreuter@yaina.de, lars@oddbit.com Subject: Re: [PATCH net] ax25: Fix refcount leak issues of ax25_dev Message-ID: <808ad381-179c-4975-a3f5-1d7cad00320b@moroto.mountain> References: <20240501060218.32898-1-duoming@zju.edu.cn> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240501060218.32898-1-duoming@zju.edu.cn> On Wed, May 01, 2024 at 02:02:18PM +0800, Duoming Zhou wrote: > @@ -58,7 +59,6 @@ void ax25_dev_device_up(struct net_device *dev) > return; > } > > - refcount_set(&ax25_dev->refcount, 1); Let's keep this here, and just delete the ax25_dev_hold(). It makes the diff smaller and I like setting the refcount earlier anyway. > dev->ax25_ptr = ax25_dev; Let's move this assignment under the spinlock where ax25_dev_hold() was. > ax25_dev->dev = dev; > netdev_hold(dev, &ax25_dev->dev_tracker, GFP_KERNEL); > @@ -88,7 +88,7 @@ void ax25_dev_device_up(struct net_device *dev) > ax25_dev->next = ax25_dev_list; > ax25_dev_list = ax25_dev; > spin_unlock_bh(&ax25_dev_lock); > - ax25_dev_hold(ax25_dev); > + refcount_set(&ax25_dev->refcount, 1); > > ax25_register_dev_sysctl(ax25_dev); > } > @@ -135,7 +135,6 @@ void ax25_dev_device_down(struct net_device *dev) > > unlock_put: > spin_unlock_bh(&ax25_dev_lock); > - ax25_dev_put(ax25_dev); > dev->ax25_ptr = NULL; > netdev_put(dev, &ax25_dev->dev_tracker); > ax25_dev_put(ax25_dev); So far as I can see, the ax25_dev should be on the list. Also, I think the dev->ax25_ptr = NULL; assignment should be under the lock. So this code should just look like: list_for_each_entry(s, &ax25_dev_list, list) { if (s->forward == dev) s->forward = NULL; } list_for_each_entry(s, &ax25_dev_list, list) { if (s == ax25_dev) { list_del(&s->list); break; } } dev->ax25_ptr = NULL; spin_unlock_bh(&ax25_dev_lock); netdev_put(dev, &ax25_dev->dev_tracker); ax25_dev_put(ax25_dev); } Also it should just be on the list once... In fact, it's impossible for one pointer to be on a list twice. So it would be nice to add a break; in ax25_addr_ax25dev(). It doesn't change the code, it just makes it more obvious. ax25_dev *ax25_addr_ax25dev(ax25_address *addr) { ax25_dev *ax25_dev, *res = NULL; spin_lock_bh(&ax25_dev_lock); list_for_each_entry(ax25_dev, &ax25_dev_list, list) { if (ax25cmp(addr, (const ax25_address *)ax25_dev->dev->dev_addr) == 0) { res = ax25_dev; ax25_dev_hold(res); break; } } spin_unlock_bh(&ax25_dev_lock); return res; } regards, dan carpenter