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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43d63dec27fsm26564853f8f.11.2026.04.12.14.05.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 12 Apr 2026 14:05:51 -0700 (PDT) Date: Sun, 12 Apr 2026 22:05:50 +0100 From: David Laight To: Jakub Kicinski Cc: Mashiro Chen , netdev@vger.kernel.org, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, horms@kernel.org, jreuter@yaina.de, linux-hams@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2 net] net: ax25: fix integer overflow in ax25_rx_fragment() Message-ID: <20260412220550.0f35f5ef@pumpkin> In-Reply-To: <20260412131751.0e90a053@kernel.org> References: <20260409025026.24575-1-mashiro.chen@mailbox.org> <20260412131751.0e90a053@kernel.org> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) 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-Transfer-Encoding: 7bit On Sun, 12 Apr 2026 13:17:51 -0700 Jakub Kicinski wrote: > On Thu, 9 Apr 2026 10:50:26 +0800 Mashiro Chen wrote: > > Fix mirrors the identical bug fixed in NET/ROM (nr_in.c): check for > > overflow before adding skb->len to fraglen, and abort fragment > > reassembly cleanly if the limit would be exceeded. > > Same problem as reported by Simon on the netrom patch applies here. > > nit: I don't think you need to cast ax25->fraglen to unsigned int > in the comparison. since it's added with skb->len it should get > auto-prompted to unsigned int. It wouldn't matter if that comparison were signed. Or change the type of ax25->fraglen to be 32bits and do the sanity check for overlong packets later in the code. I had a quick look at the header and the structure hasn't been size-optimised... David