6.12-stable review patch. If anyone has any objections, please let me know.
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From: Sabrina Dubroca sd@queasysnail.net
[ Upstream commit 94d077c331730510d5611b438640a292097341f0 ]
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 sd@queasysnail.net Reviewed-by: Florian Westphal fw@strlen.de Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 7a298058fc16c..912a4161a7420 100644 --- a/net/xfrm/xfrm_state.c +++ b/net/xfrm/xfrm_state.c @@ -1324,6 +1324,8 @@ 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 && @@ -1364,8 +1366,6 @@ xfrm_state_find(const xfrm_address_t *daddr, const xfrm_address_t *saddr, 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