git: d0076c7a8653 - stable/12 - netinet: re-read IP length after PFIL hook
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Date: Wed, 28 Jun 2023 09:16:30 UTC
The branch stable/12 has been updated by kp: URL: https://cgit.FreeBSD.org/src/commit/?id=d0076c7a86538d295ca2508dddc5d5429a2c4ff7 commit d0076c7a86538d295ca2508dddc5d5429a2c4ff7 Author: Kristof Provost <kp@FreeBSD.org> AuthorDate: 2023-06-02 14:38:30 +0000 Commit: Kristof Provost <kp@FreeBSD.org> CommitDate: 2023-06-28 09:15:59 +0000 netinet: re-read IP length after PFIL hook The pfil hook may modify the packet, so before we check its length (to decide if it needs to be fragmented or not) we should re-read that length. This is most likely to happen when pf is reassembling packets. In that scenario we'd receive the last fragment, which is likely to be a short packet, pf would reassemble it (likely exceeding the interface MTU) and then we'd transmit it without fragmenting, because we're comparing the MTU to the length of the last fragment, not the fully reassembled packet. See also: https://redmine.pfsense.org/issues/14396 Reviewed by: cy MFC after: 3 weeks Sponsored by: Rubicon Communications, LLC ("Netgate") Differential Revision: https://reviews.freebsd.org/D40395 (cherry picked from commit 185c1cddd7ef34db82bc3a25b3c92556416a4e55) --- sys/netinet/ip_output.c | 1 + 1 file changed, 1 insertion(+) diff --git a/sys/netinet/ip_output.c b/sys/netinet/ip_output.c index 93b41376f3c2..a2e4513f1118 100644 --- a/sys/netinet/ip_output.c +++ b/sys/netinet/ip_output.c @@ -584,6 +584,7 @@ sendit: case 0: /* Continue normally */ ip = mtod(m, struct ip *); + ip_len = ntohs(ip->ip_len); break; case -1: /* Need to try again */