Date: Fri, 3 Dec 2021 20:38:26 GMT From: Gleb Smirnoff <glebius@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 4c018b5aed41 - main - in_pcb: limit the effect of wraparound in TCP random port allocation check Message-ID: <202112032038.1B3KcQ4v038699@gitrepo.freebsd.org>
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The branch main has been updated by glebius: URL: https://cgit.FreeBSD.org/src/commit/?id=4c018b5aed41d96831c4a76848c0671b3d56fd7b commit 4c018b5aed41d96831c4a76848c0671b3d56fd7b Author: Peter Lei <peterlei@netflix.com> AuthorDate: 2021-12-03 20:38:12 +0000 Commit: Gleb Smirnoff <glebius@FreeBSD.org> CommitDate: 2021-12-03 20:38:12 +0000 in_pcb: limit the effect of wraparound in TCP random port allocation check The check to see if TCP port allocation should change from random to sequential port allocation mode may incorrectly cause a false positive due to negative wraparound. Example: V_ipport_tcpallocs = 2147483585 (0x7fffffc1) V_ipport_tcplastcount = 2147483553 (0x7fffffa1) V_ipport_randomcps = 100 The original code would compare (2147483585 <= -2147483643) and thus incorrectly move to sequential allocation mode. Compute the delta first before comparing against the desired limit to limit the wraparound effect (since tcplastcount is always a snapshot of a previous tcpallocs). --- sys/netinet/in_pcb.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/sys/netinet/in_pcb.c b/sys/netinet/in_pcb.c index a894163ed5a6..0a44eae0d908 100644 --- a/sys/netinet/in_pcb.c +++ b/sys/netinet/in_pcb.c @@ -2577,8 +2577,8 @@ ipport_tick(void *xtp) VNET_LIST_RLOCK_NOSLEEP(); VNET_FOREACH(vnet_iter) { CURVNET_SET(vnet_iter); /* XXX appease INVARIANTS here */ - if (V_ipport_tcpallocs <= - V_ipport_tcplastcount + V_ipport_randomcps) { + if (V_ipport_tcpallocs - V_ipport_tcplastcount <= + V_ipport_randomcps) { if (V_ipport_stoprandom > 0) V_ipport_stoprandom--; } else
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