From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4CA6C433EF for ; Fri, 26 Nov 2021 08:59:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344107AbhKZJCb (ORCPT ); Fri, 26 Nov 2021 04:02:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346095AbhKZJAa (ORCPT ); Fri, 26 Nov 2021 04:00:30 -0500 Received: from mail-wr1-x430.google.com (mail-wr1-x430.google.com [IPv6:2a00:1450:4864:20::430]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E65FC0613E0 for ; Fri, 26 Nov 2021 00:56:31 -0800 (PST) Received: by mail-wr1-x430.google.com with SMTP id u1so17013800wru.13 for ; Fri, 26 Nov 2021 00:56:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=dPlVAyhM7mWjQgSm+rkqlA38aq0g0RUSzLsuhSHe1c0=; b=M2qkUwX9kDrUlv9oKv+7vhdqedOLBEuoLyRLqQWe+3rcLclJf43nfTm65nYeIcg/yj kG7AhgGAfe5wwokn0yiIeC2JmSeiO7lbtNehWZ8hjJnTzIA2USWt1F7zj7VfoP2oHKVp /OoYcLRwiqd1T1V4cmZFT1DgBrHvNNU5eYkhyHfm8zehzmjVg6iNnbdG6pATwuDuMg3w FSVlgEpcbdKD1c+4LmjLUEKQeZ33onBpMzyzc5e48j0R0Gz7dDbOl/xulXhk+n5GMOTt pwlkyMztvPflpizFy7zNQ7o8DFEldTwIHB8Ql1t4V3/JnxzPbVyH7CPRHnBNy7KwOpQ9 hoWg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=dPlVAyhM7mWjQgSm+rkqlA38aq0g0RUSzLsuhSHe1c0=; b=3qCk4MQQgRG6i+epOnYrmKZCxxhJn2BLNcm80mMz003BG9SmR+tV4Xab71dfIY3qaJ On66fUdcGmJwYz80K4ttqSPaEVAm7cVP2fUasJpeI31+b8PI7+ZBaU0hEdBiok5bReL2 Z3mglSnCm+iJgVJQhooLuqKc01aR6MrRlScOSyPxzrMqnTdvapAdK/OlMyyFA2EejIEh dP2+3zqfM9o/RcJp5kmRKux5ZGPUtnaFYjE1fXK78Mih401HIhq5CTsFtWrxCdcq2d+V VDm250SgE00mE6CK0XCWXDbh1kxtCaRLwGxlWF/LAIeILnuEt0qaavz/F9NSalxqOM7P eT8Q== X-Gm-Message-State: AOAM532DHDHZyvKuzJ4SZhOxz5M3igju9fBIjUAVDiyPLn03EGl9o/t8 oIy4ZdaEkXMHCjtEMogoZCCOKg== X-Google-Smtp-Source: ABdhPJyYmrMo4WedZNLK4ZSZEF5jQmcupPD8SVApxovJ/ngdNZxp27pbwryBXlfh69MPDudqggeDrw== X-Received: by 2002:adf:ed52:: with SMTP id u18mr12461534wro.609.1637916990020; Fri, 26 Nov 2021 00:56:30 -0800 (PST) Received: from google.com ([2.31.167.18]) by smtp.gmail.com with ESMTPSA id d7sm4776440wrw.87.2021.11.26.00.56.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Nov 2021 00:56:29 -0800 (PST) Date: Fri, 26 Nov 2021 08:56:27 +0000 From: Lee Jones To: Dan Carpenter Cc: devel@driverdev.osuosl.org, riandrews@android.com, stable@vger.kernel.org, arve@android.com, labbott@redhat.com, sumit.semwal@linaro.org Subject: Re: [PATCH 1/1] staging: ion: Prevent incorrect reference counting behavour Message-ID: References: <20211125142004.686650-1-lee.jones@linaro.org> <20211125145004.GN6514@kadam> <20211125151822.GJ18178@kadam> <20211126071641.GO6514@kadam> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20211126071641.GO6514@kadam> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Fri, 26 Nov 2021, Dan Carpenter wrote: > On Thu, Nov 25, 2021 at 06:18:22PM +0300, Dan Carpenter wrote: > > I had thought that ->kmap_cnt was a regular int and not an unsigned > > int, but I would have to pull a stable tree to see where I misread the > > code. > > I was looking at (struct ion_buffer)->kmap_cnt but this is > (struct ion_handle)->kmap_cnt. I'm not sure how those are related but > it makes me nervous that one can go higher than the other. Also both > probably need overflow protection. > > So I guess I would just do something like: > > diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c > index 806e9b30b9dc8..e8846279b33b5 100644 > --- a/drivers/staging/android/ion/ion.c > +++ b/drivers/staging/android/ion/ion.c > @@ -489,6 +489,8 @@ static void *ion_buffer_kmap_get(struct ion_buffer *buffer) > void *vaddr; > > if (buffer->kmap_cnt) { > + if (buffer->kmap_cnt == INT_MAX) > + return ERR_PTR(-EOVERFLOW); > buffer->kmap_cnt++; > return buffer->vaddr; > } > @@ -509,6 +511,8 @@ static void *ion_handle_kmap_get(struct ion_handle *handle) > void *vaddr; > > if (handle->kmap_cnt) { > + if (handle->kmap_cnt == INT_MAX) > + return ERR_PTR(-EOVERFLOW); > handle->kmap_cnt++; > return buffer->vaddr; > } Which is all well and good until somebody changes the type. -- Lee Jones [李琼斯] Senior Technical Lead - Developer Services Linaro.org │ Open source software for Arm SoCs Follow Linaro: Facebook | Twitter | Blog