xfrm_get_ae() allocates the reply skb with xfrm_aevent_msgsize(), then build_aevent() appends attributes including XFRMA_IF_ID when x->if_id is set. xfrm_aevent_msgsize() does not include space for XFRMA_IF_ID. For states with if_id, build_aevent() can fail with -EMSGSIZE and hit BUG_ON(err < 0) in xfrm_get_ae(), turning a malformed netlink interaction into a kernel panic. Account XFRMA_IF_ID in the size calculation unconditionally and replace the BUG_ON with normal error unwinding. Fixes: 7e6526404ade ("xfrm: Add a new lookup key to match xfrm interfaces.") Reported-by: Keenan Dong Signed-off-by: Keenan Dong --- net/xfrm/xfrm_user.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index 1656b487f..d79240a1c 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -2677,7 +2677,8 @@ static inline unsigned int xfrm_aevent_msgsize(struct xfrm_state *x) + nla_total_size(4) /* XFRM_AE_RTHR */ + nla_total_size(4) /* XFRM_AE_ETHR */ + nla_total_size(sizeof(x->dir)) /* XFRMA_SA_DIR */ - + nla_total_size(4); /* XFRMA_SA_PCPU */ + + nla_total_size(4) /* XFRMA_SA_PCPU */ + + nla_total_size(sizeof(x->if_id)); /* XFRMA_IF_ID */ } static int build_aevent(struct sk_buff *skb, struct xfrm_state *x, const struct km_event *c) @@ -2789,7 +2790,12 @@ static int xfrm_get_ae(struct sk_buff *skb, struct nlmsghdr *nlh, c.portid = nlh->nlmsg_pid; err = build_aevent(r_skb, x, &c); - BUG_ON(err < 0); + if (err < 0) { + spin_unlock_bh(&x->lock); + xfrm_state_put(x); + kfree_skb(r_skb); + return err; + } err = nlmsg_unicast(xfrm_net_nlsk(net, skb), r_skb, NETLINK_CB(skb).portid); spin_unlock_bh(&x->lock); -- 2.43.0