From: Siwei Zhang Commit 14acf9652e56 ("xfrm: defensively unhash xfrm_state lists in __xfrm_state_delete") converted bydst/bysrc/byseq/byspi from hlist_del_rcu() to hlist_del_init_rcu() so that a second __xfrm_state_delete() on the same object becomes a no-op rather than a write through LIST_POISON pprev. It missed state_cache and state_cache_input, which kept hlist_del_rcu(): - hlist_del_rcu() leaves pprev = LIST_POISON2 (non-NULL), so hlist_unhashed() returns false. - hlist_del_init_rcu() leaves pprev = NULL, so hlist_unhashed() returns true. A second __xfrm_state_delete() therefore enters __hlist_del() on the already-deleted state_cache/state_cache_input nodes and does WRITE_ONCE(*pprev, next) through LIST_POISON2 — a write use-after-free once the slab is reused. The corruption can in turn cause a subsequent hlist_for_each_entry_rcu traversal to follow a dangling next pointer, producing the read use-after-free reported in xfrm_input_state_lookup(). Switch state_cache and state_cache_input to hlist_del_init_rcu() to match the other four lists, closing the write use-after-free and, with it, the read use-after-free it spawns. Assisted-by: CodeBuddy:GLM-5.2 Fixes: 0045e3d80613 ("xfrm: Cache used outbound xfrm states at the policy.") Fixes: 81a331a0e72d ("xfrm: Add an inbound percpu state cache.") Cc: stable@vger.kernel.org Signed-off-by: Siwei Zhang --- net/xfrm/xfrm_state.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c index 36a4f6793ede..f494c1ac57a4 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -823,9 +823,9 @@ int __xfrm_state_delete(struct xfrm_state *x) if (!hlist_unhashed(&x->byseq)) hlist_del_init_rcu(&x->byseq); if (!hlist_unhashed(&x->state_cache)) - hlist_del_rcu(&x->state_cache); + hlist_del_init_rcu(&x->state_cache); if (!hlist_unhashed(&x->state_cache_input)) - hlist_del_rcu(&x->state_cache_input); + hlist_del_init_rcu(&x->state_cache_input); if (!hlist_unhashed(&x->byspi)) hlist_del_init_rcu(&x->byspi); -- 2.43.7