xfrm: nat_keepalive: avoid double free on send error

nat_keepalive_send() frees the keepalive skb whenever the IPv4 or IPv6
send helper reports an error.

That cleanup is only correct before the skb is handed to the output
path. Once ip_build_and_send_pkt() or ip6_xmit() takes ownership, the
networking stack may already have consumed the skb before returning an
error, so freeing it again is unsafe.

Handle the pre-handoff failure cases inside nat_keepalive_send_ipv4()
and nat_keepalive_send_ipv6(), where the caller still owns the skb, and
keep nat_keepalive_send() responsible only for family dispatch and the
unsupported-family cleanup path.

Fixes: f531d13bdfe3 ("xfrm: support sending NAT keepalives in ESP in UDP states")
Cc: stable@vger.kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Signed-off-by: Qianyu Luo <qianyuluo3@gmail.com>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Reviewed-by: Eyal Birger <eyal.birger@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

0 files changed, 0 insertions, 0 deletions