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[159.2.239.150]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-9123bddd42fsm28905456d6.7.2026.09.16.09.21.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Sep 2026 09:21:21 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1x6sNt-00000009d5Z-0kli; Wed, 16 Sep 2026 13:21:21 -0300 Date: Wed, 16 Sep 2026 13:21:21 -0300 From: Jason Gunthorpe To: Honggang LI Cc: Leon Romanovsky , zyjzyj2000@gmail.com, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] RDMA/rxe: Fix out-of-range unsigned-to-signed conversion for RDMA message in 2GiB size Message-ID: <20260916162121.GF3196566@ziepe.ca> References: <20260915064532.194540-1-honggangli@163.com> <20260915114914.GL13683@unreal> Precedence: bulk X-Mailing-List: linux-rdma@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: On Wed, Sep 16, 2026 at 11:23:37AM +0800, Honggang LI wrote: > On Tue, Sep 15, 2026 at 02:49:14PM +0300, Leon Romanovsky wrote: > > > After fixed it, the active side of RDMA READ failed with error code > > > "IB_WC_LOC_PROT_ERR". When RDMA_READ_RESPONSE_FIRST packet recived by > > > the active side, `do_read` call `copy_data`. dma->resid is u32 0x80000000. > > > > > > int resid = dma->resid; > > > > > > This conversion set resid to -2147483648. `copy_data` abort as length > > > greater than resid. Change resid to int64_t fixes this issue. > > > > Why not size_t? > > First, size_t is u64. dma->resid is u32. If use unsigned type, u32 is enough. > > Second, I'm not sure it is right to use unsigned type. In `copy_data`, > the loop terminate on negative value of `length`. Please do not use signed values to store must-be-unsized quantities in rdma land.. > > > - payload = min_t(int, res->read.resid, mtu); > > > + payload = min_t(u32, res->read.resid, mtu); > > > > Why don't we use the proper types from the start to avoid the need for > > u32 casts? > > Again, minimal the changes with u32 casts. We need something like this > to use u32. This seems better to me Jason