The branch main has been updated by kp:
URL:
https://cgit.FreeBSD.org/src/commit/?id=358c5f5c0899339a005ef2c68ef166601bb9dca9
commit 358c5f5c0899339a005ef2c68ef166601bb9dca9
Author: Kristof Provost <k...@freebsd.org>
AuthorDate: 2024-12-10 14:02:47 +0000
Commit: Kristof Provost <k...@freebsd.org>
CommitDate: 2024-12-16 22:33:55 +0000
pf: fix cleanup deadlock
We can get to pfi_kkif_remove_if_unref() via at least two distinct paths:
- when the struct ifnet is removed, via pfi_detach_ifnet_event()
- when a rule referencing us is removed, via pfi_kkif_unref().
These two events can race against each other, leading us to free this kif
twice.
That leads to loop in V_pfi_unlinked_kifs, and an eventual deadlock.
Avoid this by making sure we only ever insert the kif into
V_pfi_unlinked_kifs
once. If we don't find it in V_pfi_ifs it's already been removed. Check
that it
exists in V_pfi_unlinked_kifs (for INVARIANTS).
Sponsored by: Rubicon Communications, LLC ("Netgate")
Differential Revision: https://reviews.freebsd.org/D48082
---
sys/netpfil/pf/pf_if.c | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/sys/netpfil/pf/pf_if.c b/sys/netpfil/pf/pf_if.c
index 650a7e4db799..d2b1b6a781f4 100644
--- a/sys/netpfil/pf/pf_if.c
+++ b/sys/netpfil/pf/pf_if.c
@@ -274,6 +274,13 @@ pf_kkif_free(struct pfi_kkif *kif)
if (! kif)
return;
+#ifdef INVARIANTS
+ if (kif->pfik_ifp) {
+ struct ifnet *ifp = kif->pfik_ifp;
+ MPASS(ifp->if_pf_kif == NULL || ifp->if_pf_kif == kif);
+ }
+#endif
+
#ifdef PF_WANT_32_TO_64_COUNTER
wowned = PF_RULES_WOWNED();
if (!wowned)
@@ -378,6 +385,35 @@ pfi_kkif_remove_if_unref(struct pfi_kkif *kif)
kif == V_pfi_all || kif->pfik_flags != 0)
return;
+ /*
+ * We can get here in at least two distinct paths:
+ * - when the struct ifnet is removed, via pfi_detach_ifnet_event()
+ * - when a rule referencing us is removed, via pfi_kkif_unref().
+ * These two events can race against each other, leading us to free
this kif
+ * twice. That leads to a loop in V_pfi_unlinked_kifs, and an eventual
+ * deadlock.
+ *
+ * Avoid this by making sure we only ever insert the kif into
+ * V_pfi_unlinked_kifs once.
+ * If we don't find it in V_pfi_ifs it's already been removed. Check
that it
+ * exists in V_pfi_unlinked_kifs.
+ */
+ if (! RB_FIND(pfi_ifhead, &V_pfi_ifs, kif)) {
+#ifdef INVARIANTS
+ struct pfi_kkif *tmp;
+ bool found = false;
+ mtx_lock(&pfi_unlnkdkifs_mtx);
+ LIST_FOREACH(tmp, &V_pfi_unlinked_kifs, pfik_list) {
+ if (tmp == kif) {
+ found = true;
+ break;
+ }
+ }
+ mtx_unlock(&pfi_unlnkdkifs_mtx);
+ MPASS(found);
+#endif
+ return;
+ }
RB_REMOVE(pfi_ifhead, &V_pfi_ifs, kif);
kif->pfik_flags |= PFI_IFLAG_REFS;
