Date: Fri, 19 Dec 2025 17:00:27 +0000 From: Michael Tuexen <tuexen@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Cc: Timo =?utf-8?Q?V=C3=B6lker?= <timo.voelker@fh-muenster.de> Subject: git: c8b3b605ae85 - main - tcp: fix checksum calculation bug Message-ID: <694584ab.d516.79ef3b93@gitrepo.freebsd.org>
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The branch main has been updated by tuexen: URL: https://cgit.FreeBSD.org/src/commit/?id=c8b3b605ae854ead6c8804e0400d80cb8fa73fdf commit c8b3b605ae854ead6c8804e0400d80cb8fa73fdf Author: Timo Völker <timo.voelker@fh-muenster.de> AuthorDate: 2025-12-19 16:50:20 +0000 Commit: Michael Tuexen <tuexen@FreeBSD.org> CommitDate: 2025-12-19 16:50:20 +0000 tcp: fix checksum calculation bug The new function in_delayed_cksum_o() was introduced to compute the checksum in the case the mbuf chain does not start with the IP header. The offset of the IP header is specified by the parameter iph_offset. If iph_offset was positive, the function computed an incorrect checksum. Reviewed by: sobomax, tuexen Fixes: 5feb38e37847 ("netinet: provide "at offset" variant of the in_delayed_cksum() API") MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D54269 --- sys/netinet/ip_output.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/sys/netinet/ip_output.c b/sys/netinet/ip_output.c index a6b29c6a7612..f1aa3c498ef7 100644 --- a/sys/netinet/ip_output.c +++ b/sys/netinet/ip_output.c @@ -1066,8 +1066,8 @@ in_delayed_cksum_o(struct mbuf *m, uint16_t iph_offset) if (csum == 0) csum = 0xffff; } else { - cklen = ntohs(ip->ip_len); - csum = in_cksum_skip(m, cklen, offset); + cklen = ntohs(ip->ip_len) - (ip->ip_hl << 2); + csum = in_cksum_skip(m, cklen + offset, offset); } offset += m->m_pkthdr.csum_data; /* checksum offset */help
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