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[142.162.112.119]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-899c739e75dsm52929296d6.46.2026.02.27.16.34.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Feb 2026 16:34:06 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vw8HV-00000001WzZ-3lBv; Fri, 27 Feb 2026 20:34:05 -0400 Date: Fri, 27 Feb 2026 20:34:05 -0400 From: Jason Gunthorpe To: Janusz Krzysztofik Cc: iommu@lists.linux.dev, Joerg Roedel , Will Deacon , Robin Murphy , David Woodhouse , Lu Baolu Subject: Re: UBSAN: shift-out-of-bounds in drivers/iommu/intel/iommu.h:1101:17 Message-ID: <20260228003405.GP44359@ziepe.ca> References: <11145826.aFP6jjVeTY@jkrzyszt-mobl2.ger.corp.intel.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <11145826.aFP6jjVeTY@jkrzyszt-mobl2.ger.corp.intel.com> On Tue, Feb 24, 2026 at 12:16:32AM +0100, Janusz Krzysztofik wrote: > Hello, > > Please have a look at > https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15478 > > For me it looks like an IOMMU issue. I've added there a comment that > summarizes my findings. If I recall there are some error flows that will push a 0 length gather to the driver, it is supposed to ignore a gather where start == end Do you think that is the issue? Jason