From: Cong Wang cong.wang@bytedance.com
[ Upstream commit 8fc29ff3910f3af08a7c40a75d436b5720efe2bf ]
strp_init() is called just a few lines above this csk->sk_user_data check, it also initializes strp->work etc., therefore, it is unnecessary to call strp_done() to cancel the freshly initialized work.
And if sk_user_data is already used by KCM, psock->strp should not be touched, particularly strp->work state, so we need to move strp_init() after the csk->sk_user_data check.
This also makes a lockdep warning reported by syzbot go away.
Reported-and-tested-by: syzbot+9fc084a4348493ef65d2@syzkaller.appspotmail.com Reported-by: syzbot+e696806ef96cdd2d87cd@syzkaller.appspotmail.com Fixes: e5571240236c ("kcm: Check if sk_user_data already set in kcm_attach") Fixes: dff8baa26117 ("kcm: Call strp_stop before strp_done in kcm_attach") Cc: Tom Herbert tom@herbertland.com Signed-off-by: Cong Wang cong.wang@bytedance.com Link: https://lore.kernel.org/r/20220827181314.193710-1-xiyou.wangcong@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/kcm/kcmsock.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c index 11a715d76a4f1..f780fbe82e7dc 100644 --- a/net/kcm/kcmsock.c +++ b/net/kcm/kcmsock.c @@ -1411,12 +1411,6 @@ static int kcm_attach(struct socket *sock, struct socket *csock, psock->sk = csk; psock->bpf_prog = prog;
- err = strp_init(&psock->strp, csk, &cb); - if (err) { - kmem_cache_free(kcm_psockp, psock); - goto out; - } - write_lock_bh(&csk->sk_callback_lock);
/* Check if sk_user_data is already by KCM or someone else. @@ -1424,13 +1418,18 @@ static int kcm_attach(struct socket *sock, struct socket *csock, */ if (csk->sk_user_data) { write_unlock_bh(&csk->sk_callback_lock); - strp_stop(&psock->strp); - strp_done(&psock->strp); kmem_cache_free(kcm_psockp, psock); err = -EALREADY; goto out; }
+ err = strp_init(&psock->strp, csk, &cb); + if (err) { + write_unlock_bh(&csk->sk_callback_lock); + kmem_cache_free(kcm_psockp, psock); + goto out; + } + psock->save_data_ready = csk->sk_data_ready; psock->save_write_space = csk->sk_write_space; psock->save_state_change = csk->sk_state_change;