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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id af79cd13be357-9153265126asm1064337685a.45.2026.06.01.10.52.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Jun 2026 10:52:52 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wU6om-000000027gs-1lLx; Mon, 01 Jun 2026 14:52:52 -0300 Date: Mon, 1 Jun 2026 14:52:52 -0300 From: Jason Gunthorpe To: David Hu Cc: Sumit Semwal , Christian =?utf-8?B?S8O2bmln?= , Nicolin Chen , Leon Romanovsky , Kevin Tian , Ankit Agrawal , Alex Williamson , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, jmoroni@google.com, praan@google.com, stable@vger.kernel.org, iommu@lists.linux.dev Subject: Re: [PATCH v4] dma-buf: Fix silent overflow for phys vec to sgt Message-ID: <20260601175252.GD2487554@ziepe.ca> References: <20260528191658.2506362-1-xuehaohu@google.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: <20260528191658.2506362-1-xuehaohu@google.com> On Thu, May 28, 2026 at 07:16:58PM +0000, David Hu wrote: > diff --git a/drivers/dma-buf/dma-buf-mapping.c b/drivers/dma-buf/dma-buf-mapping.c > index 794acff2546a..1aabc0ee70bb 100644 > --- a/drivers/dma-buf/dma-buf-mapping.c > +++ b/drivers/dma-buf/dma-buf-mapping.c > @@ -10,7 +10,7 @@ static struct scatterlist *fill_sg_entry(struct scatterlist *sgl, size_t length, > dma_addr_t addr) > { > unsigned int len, nents; > - int i; > + unsigned int i; > > nents = DIV_ROUND_UP(length, UINT_MAX); > for (i = 0; i < nents; i++) { > @@ -36,7 +36,7 @@ static unsigned int calc_sg_nents(struct dma_iova_state *state, > struct phys_vec *phys_vec, size_t nr_ranges, > size_t size) > { > - unsigned int nents = 0; > + size_t nents = 0; > size_t i; > > if (!state || !dma_use_iova(state)) { > @@ -51,6 +51,9 @@ static unsigned int calc_sg_nents(struct dma_iova_state *state, > nents = DIV_ROUND_UP(size, UINT_MAX); > } > > + if (WARN_ON_ONCE(nents > UINT_MAX)) > + return 0; The WARN seems a bit much, but if you have it then it should be arranged so the caller ultimately fails. But otherwise I think correcting the types is a good idea Jason