tcp: avoid double destroy in tcp_abort() of an unaccepted child

tcp_abort() checks for TCP_CLOSE while only owning the socket lock,
then grabs the BH lock before calling tcp_done_with_error().

For a child still sitting in a listener accept queue (which can be
reached via SOCK_DESTROY or bpf_sock_destroy()), inet_csk_listen_stop()
can run in this window: it only holds the child BH lock, and calls
inet_child_forget(), which disconnects, orphans and destroys the child.

tcp_abort() then calls tcp_done_with_error() -> tcp_done(), which sees
SOCK_DEAD and calls inet_csk_destroy_sock() a second time, leading to
a double sock_put() and a use-after-free.

Recheck TCP_CLOSE after acquiring the BH lock, unless we just closed
a listener ourselves, in which case tcp_done_with_error() must still
run to report the error.

Note that the WARN_ON(sock_owned_by_user(child)) in
inet_csk_listen_stop() can still trigger in this window.

Fixes: bac76cf89816 ("tcp: fix forever orphan socket caused by tcp_abort")
Signed-off-by: Kyle Zeng <kylebot@openai.com>
[edumazet: recheck TCP_CLOSE under the BH lock instead of moving the test, smaller diff]
Signed-off-by: Eric Dumazet <edumazet@kernel.org>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20261028160847.2170959-1-edumazet@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions