From fafbc4051123d5459ea6950899cec08ed946e278 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 3 Nov 2026 10:00:11 +0100 Subject: [PATCH] tcp: ipv6: free ireq->ipv6_opt after an RCU grace period ireq->ipv6_opt is only set by calipso_req_setattr(), when a CALIPSO NetLabel mapping is configured. Request socket migration (net.ipv4.tcp_migrate_req=1, or a BPF_SK_REUSEPORT_SELECT_OR_MIGRATE program) clones the request socket with inet_reqsk_clone(), so that the old request socket and its clone share the same ipv6_opt, then reqsk_migrate_reset() clears the pointer in the old one. Another cpu holding a reference on the old request socket can still be using these options, sending a SYNACK from tcp_v6_send_synack() or creating a child in tcp_v6_syn_recv_sock(), when the clone is freed. tcp_v6_reqsk_destructor() frees ipv6_opt with a plain kfree(), leading to a use-after-free. Both readers already run under RCU, like their IPv4 counterparts. Use kfree_rcu() in tcp_v6_reqsk_destructor(), as commit e3f33b0a1d89 ("ipv4: free inet_opt and ireq_opt after an RCU grace period") did for ireq_opt. Fixes: c905dee62232 ("tcp: Migrate TCP_NEW_SYN_RECV requests at retransmitting SYN+ACKs.") Reported-by: Sashiko Closes: https://lore.kernel.org/netdev/179369559062.488856.15441115725436277776@kernel.org/ Signed-off-by: Eric Dumazet Reviewed-by: Hangbin Liu Reviewed-by: Jiayuan Chen Reviewed-by: Kuniyuki Iwashima Tested-by: Linkui Xiao Link: https://patch.msgid.link/20261103090011.4128420-1-edumazet@kernel.org Signed-off-by: Paolo Abeni --- net/ipv6/tcp_ipv6.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index d406cd3c8cea..b1dec5d86d63 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -607,7 +607,7 @@ static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst, static void tcp_v6_reqsk_destructor(struct request_sock *req) { - kfree(inet_rsk(req)->ipv6_opt); + kfree_rcu(inet_rsk(req)->ipv6_opt, rcu); consume_skb(inet_rsk(req)->pktopts); }