From nobody Mon Dec 22 22:05:06 2025 X-Original-To: freebsd-security@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4dZsdP5WJYz6LjdW for ; Mon, 22 Dec 2025 22:05:13 +0000 (UTC) (envelope-from mike@sentex.net) Received: from smarthost1.sentex.ca (smarthost1.sentex.ca [IPv6:2607:f3e0:0:1::12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smarthost1.sentex.ca", Issuer "R13" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4dZsdP2jT8z3HY5 for ; Mon, 22 Dec 2025 22:05:13 +0000 (UTC) (envelope-from mike@sentex.net) Authentication-Results: mx1.freebsd.org; none Received: from pyroxene2a.sentex.ca (pyroxene19.sentex.ca [199.212.134.19]) by smarthost1.sentex.ca (8.18.1/8.18.1) with ESMTPS id 5BMM57uN061976 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=FAIL); Mon, 22 Dec 2025 17:05:07 -0500 (EST) (envelope-from mike@sentex.net) Received: from [IPV6:2607:f3e0:0:4:8878:3fe3:dbff:f34f] ([IPv6:2607:f3e0:0:4:8878:3fe3:dbff:f34f]) by pyroxene2a.sentex.ca (8.18.1/8.15.2) with ESMTPS id 5BMM55VR018608 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Mon, 22 Dec 2025 17:05:06 -0500 (EST) (envelope-from mike@sentex.net) Message-ID: Date: Mon, 22 Dec 2025 17:05:06 -0500 List-Id: Security issues List-Archive: https://lists.freebsd.org/archives/freebsd-security List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: freebsd-security@freebsd.org Sender: owner-freebsd-security@FreeBSD.org MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: FreeBSD-SA-25:12.rtsold.asc clarification needed To: Polarian , freebsd-security@freebsd.org References: <20251222210308.4352ee6f@Hydrogen> <479965af-2f24-4ee5-b938-adc1e5eea2a4@sentex.net> <20251222211100.3f245825@Hydrogen> <20251222215128.212a1040@Hydrogen> Content-Language: en-US From: mike tancsa Autocrypt: addr=mike@sentex.net; keydata= xsBNBFywzOMBCACoNFpwi5MeyEREiCeHtbm6pZJI/HnO+wXdCAWtZkS49weOoVyUj5BEXRZP xflV2ib2hflX4nXqhenaNiia4iaZ9ft3I1ebd7GEbGnsWCvAnob5MvDZyStDAuRxPJK1ya/s +6rOvr+eQiXYNVvfBhrCfrtR/esSkitBGxhUkBjOti8QwzD71JVF5YaOjBAs7jZUKyLGj0kW yDg4jUndudWU7G2yc9GwpHJ9aRSUN8e/mWdIogK0v+QBHfv/dsI6zVB7YuxCC9Fx8WPwfhDH VZC4kdYCQWKXrm7yb4TiVdBh5kgvlO9q3js1yYdfR1x8mjK2bH2RSv4bV3zkNmsDCIxjABEB AAHNHW1pa2UgdGFuY3NhIDxtaWtlQHNlbnRleC5uZXQ+wsCOBBMBCAA4FiEEmuvCXT0aY6hs 4SbWeVOEFl5WrMgFAl+pQfkCGwMFCwkIBwIGFQoJCAsCBBYCAwECHgECF4AACgkQeVOEFl5W rMiN6ggAk3H5vk8QnbvGbb4sinxZt/wDetgk0AOR9NRmtTnPaW+sIJEfGBOz47Xih+f7uWJS j+uvc9Ewn2Z7n8z3ZHJlLAByLVLtcNXGoRIGJ27tevfOaNqgJHBPbFOcXCBBFTx4MYMM4iAZ cDT5vsBTSaM36JZFtHZBKkuFEItbA/N8ZQSHKdTYMIA7A3OCLGbJBqloQ8SlW4MkTzKX4u7R yefAYQ0h20x9IqC5Ju8IsYRFacVZconT16KS81IBceO42vXTN0VexbVF2rZIx3v/NT75r6Vw 0FlXVB1lXOHKydRA2NeleS4NEG2vWqy/9Boj0itMfNDlOhkrA/0DcCurMpnpbM7ATQRcsMzk AQgA1Dpo/xWS66MaOJLwA28sKNMwkEk1Yjs+okOXDOu1F+0qvgE8sVmrOOPvvWr4axtKRSG1 t2QUiZ/ZkW/x/+t0nrM39EANV1VncuQZ1ceIiwTJFqGZQ8kb0+BNkwuNVFHRgXm1qzAJweEt RdsCMohB+H7BL5LGCVG5JaU0lqFU9pFP40HxEbyzxjsZgSE8LwkI6wcu0BLv6K6cLm0EiHPO l5G8kgRi38PS7/6s3R8QDsEtbGsYy6O82k3zSLIjuDBwA9GRaeigGppTxzAHVjf5o9KKu4O7 gC2KKVHPegbXS+GK7DU0fjzX57H5bZ6komE5eY4p3oWT/CwVPSGfPs8jOwARAQABwsB2BBgB CAAgFiEEmuvCXT0aY6hs4SbWeVOEFl5WrMgFAl+pQfkCGwwACgkQeVOEFl5WrMiVqwf9GwU8 c6cylknZX8QwlsVudTC8xr/L17JA84wf03k3d4wxP7bqy5AYy7jboZMbgWXngAE/HPQU95NM aukysSnknzoIpC96XZJ0okLBXVS6Y0ylZQ+HrbIhMpuQPoDweoF5F9wKrsHRoDaUK1VR706X rwm4HUzh7Jk+auuMYfuCh0FVlFBEuiJWMLhg/5WCmcRfiuB6F59ZcUQrwLEZeNhF2XJV4KwB Tlg7HCWO/sy1foE5noaMyACjAtAQE9p5kGYaj+DuRhPdWUTsHNuqrhikzIZd2rrcMid+ktb0 NvtvswzMO059z1YGMtGSqQ4srCArju+XHIdTFdiIYbd7+jeehg== In-Reply-To: <20251222215128.212a1040@Hydrogen> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.86 X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[] X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Queue-Id: 4dZsdP2jT8z3HY5 On 12/22/2025 4:51 PM, Polarian wrote: > Hey, > >> I am trying to understand if rtsold is not running and not enabled, >> what from the kernel would spin that up to expose the code path that >> is patched in the advisory? > I don't get where you are getting a kernel vulnerability from. > > The advisory already explains that the RCE comes from a lack of input > validation on the domain search field. This is a userspace > vulnerability. > > This passed to resolvconf which does not validate its input, which > therefore allows for an RCE. > > So why we talking about code paths within the kernel? Its not within > the networking stack, it is a vulnerability within the userspace > utilities. When I asked if patching the userland code was enough, you said no. From what I understand having ACCEPT_RTADV on an interface means the kernel is processing rtadv packets.  The advisory mentions that, but it seems thats not sufficient to trigger the bug, as rtsold is the one that processes the unchecked DNS info.  i.e. you need both ACCEPT_RTADV enabled and rtsold enabled, no ? If just having ACCEPT_RTADV enabled would lead to an exploit, that implies a kernel bug no ? I just want to confirm if *not* running rtsold is enough to avoid this bug or just having the mere presence of IPv6 can lead to exploit. If the latter, how is that actually working.     ---Mike