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Date: Sat, 27 Apr 2024 14:14:59 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: Aleksandr Mishin <amishin@t-argos.ru>, Rob Herring <robh@kernel.org>,
	Lorenzo Pieralisi <lpieralisi@kernel.org>,
	Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= <u.kleine-koenig@pengutronix.de>,
	Serge Semin <fancer.lancer@gmail.com>,
	Niklas Cassel <cassel@kernel.org>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
	Damien Le Moal <dlemoal@kernel.org>,
	Siddharth Vadapalli <s-vadapalli@ti.com>, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org, lvc-project@linuxtesting.org
Subject: Re: [PATCH v2] PCI: dwc: keystone: Fix potential NULL dereference
Message-ID: <20240427084459.GD1981@thinkpad>
References: <20240425092135.13348-1-amishin@t-argos.ru>
 <63b89455-3e30-421a-a082-00d39e836e20@intel.com>
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In-Reply-To: <63b89455-3e30-421a-a082-00d39e836e20@intel.com>

On Thu, Apr 25, 2024 at 03:00:14PM +0200, Alexander Lobakin wrote:
> From: Aleksandr Mishin <amishin@t-argos.ru>
> Date: Thu, 25 Apr 2024 12:21:35 +0300
> 
> > In ks_pcie_setup_rc_app_regs() resource_list_first_type() may return
> > NULL which is later dereferenced. Fix this bug by adding NULL check.
> > 
> > Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Please stop spamming with "potential fixes" made mechanically from
> static analyzer reports without looking into the code flow. These
> patches are mostly incorrect and may hurt.
> Either have a stable repro and then fix the real bug or don't touch
> anything at all.
> 

This patch obviously fixes the potential issue where resource_list_first_type()
may return NULL if the MEM range is not provided in DT.
pci_parse_request_of_pci_ranges() will just emit a warning in that case and this
code path will cause a NULL pointer dereference.

Even though this situation means that the DT is broken, it still makes sense to
have the checks in place.

- Mani

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