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[34.85.235.172]) by smtp.gmail.com with ESMTPSA id 00721157ae682-7c7f54c29ddsm44414217b3.34.2026.05.16.06.41.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 16 May 2026 06:41:07 -0700 (PDT) Date: Sat, 16 May 2026 09:41:07 -0400 From: Willem de Bruijn To: Jakub Kicinski , Qi Tang Cc: "David S . Miller" , David Ahern , Eric Dumazet , Paolo Abeni , Simon Horman , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: In-Reply-To: <20260515175522.0aafbfb4@kernel.org> References: <20260514035802.1540395-1-tpluszz77@gmail.com> <20260515175522.0aafbfb4@kernel.org> Subject: Re: [PATCH net v4] ipv6: validate extension header length before copying to cmsg 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=utf-8 Content-Transfer-Encoding: 7bit Jakub Kicinski wrote: > On Thu, 14 May 2026 11:58:02 +0800 Qi Tang wrote: > > + return (ptr + len <= skb_tail_pointer(skb)) ? len : 0; > > This is probably better written as: > > return (len <= skb_tail_pointer(skb) - ptr) ? len : 0; > > ? len can't be too large so unlikely to matter in practice > but technically ptr + len may overflow and wrap on 32b? If making changes, also time to replace the open coded offset with sizeof ipv6_opt_hdr and opt_hdr->hdrlen? Or perhaps better left for net-next.