From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CCE7247D444 for ; Thu, 6 Aug 2026 15:38:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786030725; cv=none; b=RgsSgNCkoh6zJdKwHzLKlP3iwqKDg+cm/01ydYMT93RJGDl2hWCr6ET4Dh1GkBfAhelpFtOm6Tez+tAHkPWBPn24CYJmbHRBL3fskKupjps8uXtGODJYp2nlIHeKwuqKOZJb/RLEmmomm/bfhXh99TbFRCRT90AFVXMkN/vPbwY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786030725; c=relaxed/simple; bh=HkLd7vLJFCtccjkU6wFw/hXH3/rpNOn5YATvCZNVC+A=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=jVerCHyI8g+xUgnNLfTh2qe+Bi0m5fN7e82+tTmxuRvXOqKmMk3wqtDmNw++Mv+orptzYnUEFNRF0Nx5pD0NmKndq+TG0yfuJeWvm09+ZSMv7pkzt6hF0T0ckvHdhVSIXBtTTGAp7gmVlaJO+c/8SBN6u5W2cSeB3JcgiJ18vqU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=CFPIzaNY; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="CFPIzaNY" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id ABC36153B; Thu, 6 Aug 2026 08:38:37 -0700 (PDT) Received: from [192.168.178.24] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0CEEB3F632; Thu, 6 Aug 2026 08:38:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1786030721; bh=HkLd7vLJFCtccjkU6wFw/hXH3/rpNOn5YATvCZNVC+A=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=CFPIzaNY91u1RSDpvqJJ7p/ocphehLxg9n9kmE7Ly9JxhpAaQr2tu0N5Lk7gLMghr cHiD9Fyeh5iX8Pm4iDItyJoEwVg4WrcKysZMdylN5SJWI9evy4nGvusdMnGqNSy377 mBcX9+hP8wlyHCd2ex+1lUttkfMhcp+VQdc77TkY= Message-ID: <51f5d369-9491-49cb-957a-dd70ad42ecd6@arm.com> Date: Thu, 6 Aug 2026 17:38:27 +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 v1 1/2] arm_mpam: Fix a NULL pointer dereference on unbinding after an error interrupt To: Ben Horgan Cc: james.morse@arm.com, reinette.chatre@intel.com, fenghuay@nvidia.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, dave.martin@arm.com, will@kernel.org, catalin.marinas@kernel.org References: <20260806144631.2502918-1-ben.horgan@arm.com> <20260806144631.2502918-2-ben.horgan@arm.com> Content-Language: en-GB From: Andre Przywara In-Reply-To: <20260806144631.2502918-2-ben.horgan@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi, On 8/6/26 16:46, Ben Horgan wrote: > If a user unbinds an MSC after mpam_disable() has been run in response > to an error interrupt then a dereference of a NULL pointer occurs as > mpam_disable() sets the drvdata to NULL. Add an early return to the driver > remove callback to avoid this. Yes, I added a very similar patch to my stack yesterday, in response to a Sashiko complaint. However I was still calling mpam_free_garbage() at the end, to me it looks like this is not depending on any MSC? Cheers, Andre > Fixes: f04046f2577a ("arm_mpam: Add probe/remove for mpam msc driver and kbuild boiler plate") > Signed-off-by: Ben Horgan > --- > drivers/resctrl/mpam_devices.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c > index 2f09f4b78bd3..bc6cc0b5c96b 100644 > --- a/drivers/resctrl/mpam_devices.c > +++ b/drivers/resctrl/mpam_devices.c > @@ -2025,6 +2025,9 @@ static void mpam_msc_drv_remove(struct platform_device *pdev) > { > struct mpam_msc *msc = platform_get_drvdata(pdev); > > + if (!msc) > + return; > + > mutex_lock(&mpam_list_lock); > mpam_msc_destroy(msc); > mutex_unlock(&mpam_list_lock);