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In-Reply-To: <5a34a77e-d1bf-c630-ef9b-4f94c2c0c221@canonical.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/05/2019 00:42, Colin Ian King wrote: > Hi, > > Static analysis with Coverity picked up an issue in the following commit: > > commit 2bde9b3ec8bdf60788e9e2ce8c07a2f8d6003dbd > Author: Cédric Le Goater > Date: Thu Apr 18 12:39:41 2019 +0200 > > KVM: Introduce a 'release' method for KVM devices > > > struct kvm *kvm = dev->kvm; > > + if (!dev) > + return -ENODEV; > > If dev is null then the dereference of dev->kvm when assigning pointer > kvm will cause an null pointer dereference. This is easily fixed by > assigning kvm after the dev null check. Yes, this is a bug. > > + > + if (dev->kvm != kvm) > + return -EPERM; > > I don't understand the logic of the above check. kvm is the same > dev->kvm on the earlier assignment, so dev->kvm != kvm seems to be > always false, so this check seems to be redundant. Am I missing > something more fundamental here? Nope. This looks like unfortunate cut-n-paste which slipped through out reviewing process :-D -- Alexey