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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , netdev@vger.kernel.org, dev@openvswitch.org, linux-kernel@vger.kernel.org References: <179328922134.76862.10417963652853801970@gmail.com> Content-Language: en-US From: Ilya Maximets Autocrypt: addr=i.maximets@ovn.org; keydata= xsFNBF77bOMBEADVZQ4iajIECGfH3hpQMQjhIQlyKX4hIB3OccKl5XvB/JqVPJWuZQRuqNQG /B70MP6km95KnWLZ4H1/5YOJK2l7VN7nO+tyF+I+srcKq8Ai6S3vyiP9zPCrZkYvhqChNOCF pNqdWBEmTvLZeVPmfdrjmzCLXVLi5De9HpIZQFg/Ztgj1AZENNQjYjtDdObMHuJQNJ6ubPIW cvOOn4WBr8NsP4a2OuHSTdVyAJwcDhu+WrS/Bj3KlQXIdPv3Zm5x9u/56NmCn1tSkLrEgi0i /nJNeH5QhPdYGtNzPixKgPmCKz54/LDxU61AmBvyRve+U80ukS+5vWk8zvnCGvL0ms7kx5sA tETpbKEV3d7CB3sQEym8B8gl0Ux9KzGp5lbhxxO995KWzZWWokVUcevGBKsAx4a/C0wTVOpP FbQsq6xEpTKBZwlCpxyJi3/PbZQJ95T8Uw6tlJkPmNx8CasiqNy2872gD1nN/WOP8m+cIQNu o6NOiz6VzNcowhEihE8Nkw9V+zfCxC8SzSBuYCiVX6FpgKzY/Tx+v2uO4f/8FoZj2trzXdLk BaIiyqnE0mtmTQE8jRa29qdh+s5DNArYAchJdeKuLQYnxy+9U1SMMzJoNUX5uRy6/3KrMoC/ 7zhn44x77gSoe7XVM6mr/mK+ViVB7v9JfqlZuiHDkJnS3yxKPwARAQABzSJJbHlhIE1heGlt ZXRzIDxpLm1heGltZXRzQG92bi5vcmc+wsGUBBMBCAA+AhsDBQsJCAcCBhUKCQgLAgQWAgMB Ah4BAheAFiEEh+ma1RKWrHCY821auffsd8gpv5YFAmfB9JAFCQyI7q0ACgkQuffsd8gpv5YQ og/8DXt1UOznvjdXRHVydbU6Ws+1iUrxlwnFH4WckoFgH4jAabt25yTa1Z4YX8Vz0mbRhTPX M/j1uORyObLem3of4YCd4ymh7nSu++KdKnNsZVHxMcoiic9ILPIaWYa8kTvyIDT2AEVfn9M+ vskM0yDbKa6TAHgr/0jCxbS+mvN0ZzDuR/LHTgy3e58097SWJohj0h3Dpu+XfuNiZCLCZ1/G AbBCPMw+r7baH/0evkX33RCBZwvh6tKu+rCatVGk72qRYNLCwF0YcGuNBsJiN9Aa/7ipkrA7 Xp7YvY3Y1OrKnQfdjp3mSXmknqPtwqnWzXvdfkWkZKShu0xSk+AjdFWCV3NOzQaH3CJ67NXm aPjJCIykoTOoQ7eEP6+m3WcgpRVkn9bGK9ng03MLSymTPmdINhC5pjOqBP7hLqYi89GN0MIT Ly2zD4m/8T8wPV9yo7GRk4kkwD0yN05PV2IzJECdOXSSStsf5JWObTwzhKyXJxQE+Kb67Wwa LYJgltFjpByF5GEO4Xe7iYTjwEoSSOfaR0kokUVM9pxIkZlzG1mwiytPadBt+VcmPQWcO5pi WxUI7biRYt4aLriuKeRpk94ai9+52KAk7Lz3KUWoyRwdZINqkI/aDZL6meWmcrOJWCUMW73e 4cMqK5XFnGqolhK4RQu+8IHkSXtmWui7LUeEvO/OwU0EXvts4wEQANCXyDOic0j2QKeyj/ga OD1oKl44JQfOgcyLVDZGYyEnyl6b/tV1mNb57y/YQYr33fwMS1hMj9eqY6tlMTNz+ciGZZWV YkPNHA+aFuPTzCLrapLiz829M5LctB2448bsgxFq0TPrr5KYx6AkuWzOVq/X5wYEM6djbWLc VWgJ3o0QBOI4/uB89xTf7mgcIcbwEf6yb/86Cs+jaHcUtJcLsVuzW5RVMVf9F+Sf/b98Lzrr 2/mIB7clOXZJSgtV79Alxym4H0cEZabwiXnigjjsLsp4ojhGgakgCwftLkhAnQT3oBLH/6ix 87ahawG3qlyIB8ZZKHsvTxbWte6c6xE5dmmLIDN44SajAdmjt1i7SbAwFIFjuFJGpsnfdQv1 OiIVzJ44kdRJG8kQWPPua/k+AtwJt/gjCxv5p8sKVXTNtIP/sd3EMs2xwbF8McebLE9JCDQ1 RXVHceAmPWVCq3WrFuX9dSlgf3RWTqNiWZC0a8Hn6fNDp26TzLbdo9mnxbU4I/3BbcAJZI9p 9ELaE9rw3LU8esKqRIfaZqPtrdm1C+e5gZa2gkmEzG+WEsS0MKtJyOFnuglGl1ZBxR1uFvbU VXhewCNoviXxkkPk/DanIgYB1nUtkPC+BHkJJYCyf9Kfl33s/bai34aaxkGXqpKv+CInARg3 fCikcHzYYWKaXS6HABEBAAHCwXwEGAEIACYCGwwWIQSH6ZrVEpascJjzbVq59+x3yCm/lgUC Z8H0qQUJDIjuxgAKCRC59+x3yCm/loAdD/wJCOhPp9711J18B9c4f+eNAk5vrC9Cj3RyOusH Hebb9HtSFm155Zz3xiizw70MSyOVikjbTocFAJo5VhkyuN0QJIP678SWzriwym+EG0B5P97h FSLBlRsTi4KD8f1Ll3OT03lD3o/5Qt37zFgD4mCD6OxAShPxhI3gkVHBuA0GxF01MadJEjMu jWgZoj75rCLG9sC6L4r28GEGqUFlTKjseYehLw0s3iR53LxS7HfJVHcFBX3rUcKFJBhuO6Ha /GggRvTbn3PXxR5UIgiBMjUlqxzYH4fe7pYR7z1m4nQcaFWW+JhY/BYHJyMGLfnqTn1FsIwP dbhEjYbFnJE9Vzvf+RJcRQVyLDn/TfWbETf0bLGHeF2GUPvNXYEu7oKddvnUvJK5U/BuwQXy TRFbae4Ie96QMcPBL9ZLX8M2K4XUydZBeHw+9lP1J6NJrQiX7MzexpkKNy4ukDzPrRE/ruui yWOKeCw9bCZX4a/uFw77TZMEq3upjeq21oi6NMTwvvWWMYuEKNi0340yZRrBdcDhbXkl9x/o skB2IbnvSB8iikbPng1ihCTXpA2yxioUQ96Akb+WEGopPWzlxTTK+T03G2ljOtspjZXKuywV Wu/eHyqHMyTu8UVcMRR44ki8wam0LMs+fH4dRxw5ck69AkV+JsYQVfI7tdOu7+r465LUfg== In-Reply-To: <179328922134.76862.10417963652853801970@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/29/26 4:53 PM, Joas Antonio dos Santos wrote: > get_ipv6_ext_hdrs() walks the IPv6 extension header chain to fill > key->ipv6.exthdrs, but advances to the next header with ipv6_optlen() > whatever the current header is. That is only right for Hop-by-Hop, > Destination Options and Routing headers: > > - an Authentication Header is ((hdrlen + 2) << 2) bytes long > (ipv6_authlen()), so with hdrlen = 4 the walk skips 40 bytes instead > of 24 and reads the next "header" from the ICV and payload; > > - a Fragment header is always 8 bytes, and the byte read as hdrlen is > its Reserved field, which the sender controls and receivers ignore, > so a non-zero value makes the walk skip up to 2048 bytes and miss > the headers that follow. > > In both cases the OFPIEH12_* bits stored in key->ipv6.exthdrs depend on > bytes chosen by the sender rather than on the headers that are actually > present: payload bytes that look like another AH or a Hop-by-Hop header > add OFPIEH12_UNREP/OFPIEH12_UNSEQ, and real headers after a Fragment > header can go unreported. Flows that match on OVS_KEY_ATTR_IPV6_EXTHDRS > then classify such packets wrongly. There is no memory safety issue, > skb_header_pointer() bounds every read. > > Advance by sizeof(struct frag_hdr) for Fragment headers and by > ipv6_authlen() for AH, as ipv6_find_hdr() does. > > Fixes: 28a3f0601727 ("net: openvswitch: IPv6: Add IPv6 extension header support") > Link: https://lore.kernel.org/all/178905555085.219967.6617611783437228045@kernel.org/ > Cc: stable@vger.kernel.org > Signed-off-by: Joas Antonio dos Santos > Assisted-by: Yaga Agent HackerSec Claude:claude-opus-5-5 The tag is no longer needed. And it has a wrong format anyway. > --- > Found while going through the pre-existing issues the Sashiko review of > "openvswitch: fix wrong flag value in get_ipv6_ext_hdrs()" pointed out > (Link above); Eelco mentioned putting them on his todo list, and I did > not find a fix for this part in net, net-next or on the list. Happy to > drop this if a fix is already in flight. > > Tested by building get_ipv6_ext_hdrs() before and after this patch in a > userspace harness (skb_header_pointer() replaced by a bounds-checked > memcpy from a buffer) and feeding it crafted packets: > > AH(hdrlen=4) + DSTOPTS + TCP, payload mimicking AH at old offset > before: AUTH DEST UNREP UNSEQ after: AUTH DEST UNSEQ > FRAG(Reserved=0xff) + DSTOPTS + ROUTING + TCP > before: DEST FRAG UNSEQ after: DEST FRAG ROUTER UNSEQ > FRAG(Reserved=0) + ROUTING + TCP, HOP + DST + ROUTING + TCP > unchanged > > net/openvswitch/ builds cleanly with W=1 (arm64, net/main 94cea342e891). > I did not test it on a live datapath. > > net/openvswitch/flow.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c > index 1c4f3a079..a1c60d2f5 100644 > --- a/net/openvswitch/flow.c > +++ b/net/openvswitch/flow.c > @@ -372,8 +372,13 @@ static void get_ipv6_ext_hdrs(struct sk_buff *skb, struct ipv6hdr *nh, > hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr); > if (!hp) > break; > + if (next_type == IPPROTO_FRAGMENT) > + start += sizeof(struct frag_hdr); Should we also stop it's not a first fragment? There is no actual next header after the fragment one if it's not the first. Otherwise, the patch seems incomplete. Best regards, Ilya Maximets.