proto: correct 802.1Q length check in is_ipv_X#1044
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any update? |
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Thanks for the finding. As the welcome message tells you, we don't deal with github PRs, but ask for patches to be sent to our gerrit or to the mailing list. I can forward to gerrit, but we had lots of other work to do, so this extra step can lead to patches getting overlooked (which is a shame, but days are short). Before proceeding, I need a |
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Github: OpenVPN/openvpn#1044 This has also been reported twice as a security relevant bug, but only later than the original finding - and it isn't. While --client-nat would modify a 32bit integer "after the packet" (the place where an IPv4 address would be, in a well-formed packet), the underlying buffer is always max-frame sized, and we never look at the "modified integer" afterwards, so there are no consequences warranting allocation of a CVE ID. Signed-off-by: rootvector2 <dxbnaveed.k@gmail.com> Acked-by: Arne Schwabe <arne-openvpn@rfc2549.org> Acked-by: Antonio Quartulli <antonio@mandelbit.com> Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1789 Reported-By: 章鱼哥 (www.aipyaipy.com) Reported-By: Yu Zhang Wong <wongyuzhang45@gmail.com> Change-Id: I8219c6295acf28ff10ddb2fcc285f813c42fa8fe Message-Id: <20260715202210.9010-1-gert@greenie.muc.de> URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg37652.html Signed-off-by: Gert Doering <gert@greenie.muc.de>
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Github: OpenVPN/openvpn#1044 This has also been reported twice as a security relevant bug, but only later than the original finding - and it isn't. While --client-nat would modify a 32bit integer "after the packet" (the place where an IPv4 address would be, in a well-formed packet), the underlying buffer is always max-frame sized, and we never look at the "modified integer" afterwards, so there are no consequences warranting allocation of a CVE ID. Signed-off-by: rootvector2 <dxbnaveed.k@gmail.com> Acked-by: Arne Schwabe <arne-openvpn@rfc2549.org> Acked-by: Antonio Quartulli <antonio@mandelbit.com> Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1789 Reported-By: 章鱼哥 (www.aipyaipy.com) Reported-By: Yu Zhang Wong <wongyuzhang45@gmail.com> Change-Id: I8219c6295acf28ff10ddb2fcc285f813c42fa8fe Message-Id: <20260715202210.9010-1-gert@greenie.muc.de> URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg37652.html Signed-off-by: Gert Doering <gert@greenie.muc.de> (cherry picked from commit f8b15da)
cron2
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Github: OpenVPN/openvpn#1044 This has also been reported twice as a security relevant bug, but only later than the original finding - and it isn't. While --client-nat would modify a 32bit integer "after the packet" (the place where an IPv4 address would be, in a well-formed packet), the underlying buffer is always max-frame sized, and we never look at the "modified integer" afterwards, so there are no consequences warranting allocation of a CVE ID. Signed-off-by: rootvector2 <dxbnaveed.k@gmail.com> Acked-by: Arne Schwabe <arne-openvpn@rfc2549.org> Acked-by: Antonio Quartulli <antonio@mandelbit.com> Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1789 Reported-By: 章鱼哥 (www.aipyaipy.com) Reported-By: Yu Zhang Wong <wongyuzhang45@gmail.com> Change-Id: I8219c6295acf28ff10ddb2fcc285f813c42fa8fe Message-Id: <20260715202210.9010-1-gert@greenie.muc.de> URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg37652.html Signed-off-by: Gert Doering <gert@greenie.muc.de> (cherry picked from commit f8b15da)
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Patch went to gerrit, has been reviewed and approved, and is now undergoing final github actions checks. Expect it to show up in the "real" openvpn repo tomorrow. |
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In TAP mode is_ipv_X() checks an 802.1Q frame against the untagged Ethernet header size but then advances past the larger 18-byte 802.1Q header. A tagged frame of 34 to 37 bytes passes the check yet leaves fewer than sizeof(struct openvpn_iphdr) bytes at the new buffer head, so callers such as client_nat_transform that trust the return value access bytes past the IP header. Use sizeof(struct openvpn_8021qhdr) for the check instead.