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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id af79cd13be357-91589ea0bcfsm2492548385a.0.2026.06.10.09.37.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Jun 2026 09:37:51 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wXLw6-000000048Ns-2Eex; Wed, 10 Jun 2026 13:37:50 -0300 Date: Wed, 10 Jun 2026 13:37:50 -0300 From: Jason Gunthorpe To: Samuel Moelius Cc: Kevin Tian , "Joerg Roedel (AMD)" , Will Deacon , Robin Murphy , "open list:IOMMUFD" , open list Subject: Re: [PATCH v2] iommu/iommufd: avoid selftest dirty bitmap size wrap Message-ID: <20260610163750.GP2764304@ziepe.ca> References: <20260610002351.1672863.5f5d62d5e4be.iommufd-test-dirty-bitmap-size-wrap@trailofbits.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <20260610002351.1672863.5f5d62d5e4be.iommufd-test-dirty-bitmap-size-wrap@trailofbits.com> On Wed, Jun 10, 2026 at 12:23:52AM +0000, Samuel Moelius wrote: > @@ -1705,6 +1707,13 @@ static int iommufd_test_dirty(struct iommufd_ucmd *ucmd, unsigned int mockpt_id, > goto out_put; > } > > + if (check_mul_overflow((unsigned long)SZ_16M, page_size, &max_length)) > + max_length = ULONG_MAX; You should never have a cast in a check_.._overflow like this. Also just fail, something is really wrong if page size is so large this doesn't succeed. Jason