Date: Wed, 10 Jan 2024 21:10:22 +0000 From: bugzilla-noreply@freebsd.org To: net@FreeBSD.org Subject: [Bug 276248] race of IPv6 address removal with nd6_timer(), panic in in6_unlinkin6_unlink_ifa Message-ID: <bug-276248-7501@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D276248 Bug ID: 276248 Summary: race of IPv6 address removal with nd6_timer(), panic in in6_unlinkin6_unlink_ifa Product: Base System Version: 15.0-CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: net@FreeBSD.org Reporter: glebius@FreeBSD.org nd6_timer() uses network epoch to go through list of IPv6 address: CK_STAILQ_FOREACH_SAFE(ia6, &V_in6_ifaddrhead, ia_link, nia6) { Note that epoch(9) introduction to the kernel this list traversal didn't use any locking, hence comment XXXRW: in6_ifaddrhead locking. The epoch locking guarantees safe memory access, but doesn't prevent from addresses being removed. Then nd6_timer() may call in6_purgeaddr() which will try to remove address that already could had been removed, e.g. by in6_control(). This race manifests in panic: #17 0xffffffff80c33c58 in trap_check (frame=3D0xfffffe000effdb70) at /usr/src/FreeBSD/sys/amd64/amd64/trap.c:662 #19 0xffffffff8097e623 in in6_unlink_ifa (ia=3D0xfffff80002520900, ifp=3D0xfffff8004d72d000) at /usr/src/FreeBSD/sys/netinet6/in6.c:1445 #20 0xffffffff8097ee0b in in6_purgeaddr (ifa=3D0xfffff80002520900) at /usr/src/FreeBSD/sys/netinet6/in6.c:1405 #21 0xffffffff809ad781 in nd6_timer (arg=3D0xfffff8015064dc00) at /usr/src/FreeBSD/sys/netinet6/nd6.c:961 #22 0xffffffff80673536 in softclock_call_cc (c=3D0xfffffe00b98be828, cc=3D0xffffffff816800c0, direct=3D0) at /usr/src/FreeBSD/sys/kern/kern_timeout.c:717 #23 0xffffffff80675e46 in softclock_thread (arg=3D0xffffffff816800c0) at /usr/src/FreeBSD/sys/kern/kern_timeout.c:856 --=20 You are receiving this mail because: You are the assignee for the bug.=
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