From: Sabrina Dubroca Date: Fri, 23 May 2025 15:11:17 +0000 (+0200) Subject: xfrm: state: initialize state_ptrs earlier in xfrm_state_find X-Git-Tag: v6.16~15^2^2~5^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=94d077c331730510d5611b438640a292097341f0;p=thirdparty%2Fkernel%2Flinux.git xfrm: state: initialize state_ptrs earlier in xfrm_state_find In case of preemption, xfrm_state_look_at will find a different pcpu_id and look up states for that other CPU. If we matched a state for CPU2 in the state_cache while the lookup started on CPU1, we will jump to "found", but the "best" state that we got will be ignored and we will enter the "acquire" block. This block uses state_ptrs, which isn't initialized at this point. Let's initialize state_ptrs just after taking rcu_read_lock. This will also prevent a possible misuse in the future, if someone adjusts this function. Reported-by: syzbot+7ed9d47e15e88581dc5b@syzkaller.appspotmail.com Fixes: e952837f3ddb ("xfrm: state: fix out-of-bounds read during lookup") Signed-off-by: Sabrina Dubroca Reviewed-by: Florian Westphal Signed-off-by: Steffen Klassert --- diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c index 203b585c2ae28..2e2e95d2a06fc 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -1389,6 +1389,8 @@ xfrm_state_find(const xfrm_address_t *daddr, const xfrm_address_t *saddr, sequence = read_seqcount_begin(&net->xfrm.xfrm_state_hash_generation); rcu_read_lock(); + xfrm_hash_ptrs_get(net, &state_ptrs); + hlist_for_each_entry_rcu(x, &pol->state_cache_list, state_cache) { if (x->props.family == encap_family && x->props.reqid == tmpl->reqid && @@ -1429,8 +1431,6 @@ cached: else if (acquire_in_progress) /* XXX: acquire_in_progress should not happen */ WARN_ON(1); - xfrm_hash_ptrs_get(net, &state_ptrs); - h = __xfrm_dst_hash(daddr, saddr, tmpl->reqid, encap_family, state_ptrs.hmask); hlist_for_each_entry_rcu(x, state_ptrs.bydst + h, bydst) { #ifdef CONFIG_XFRM_OFFLOAD