* [Patch net] kcm: get rid of unnecessary cleanup
@ 2022-08-22 4:06 Cong Wang
2022-08-23 23:39 ` Jakub Kicinski
0 siblings, 1 reply; 2+ messages in thread
From: Cong Wang @ 2022-08-22 4:06 UTC (permalink / raw)
To: netdev
Cc: Cong Wang, syzbot+9fc084a4348493ef65d2,
syzbot+e696806ef96cdd2d87cd, Jakub Kicinski, Tom Herbert
From: Cong Wang <cong.wang@bytedance.com>
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.
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: Jakub Kicinski <kuba@kernel.org>
Cc: Tom Herbert <tom@herbertland.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
---
net/kcm/kcmsock.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index 71899e5a5a11..661c40cdab3e 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1425,8 +1425,6 @@ 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;
--
2.34.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [Patch net] kcm: get rid of unnecessary cleanup
2022-08-22 4:06 [Patch net] kcm: get rid of unnecessary cleanup Cong Wang
@ 2022-08-23 23:39 ` Jakub Kicinski
0 siblings, 0 replies; 2+ messages in thread
From: Jakub Kicinski @ 2022-08-23 23:39 UTC (permalink / raw)
To: Cong Wang
Cc: netdev, Cong Wang, syzbot+9fc084a4348493ef65d2,
syzbot+e696806ef96cdd2d87cd, Tom Herbert
On Sun, 21 Aug 2022 21:06:28 -0700 Cong Wang wrote:
> From: Cong Wang <cong.wang@bytedance.com>
>
> 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.
>
> 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: Jakub Kicinski <kuba@kernel.org>
> Cc: Tom Herbert <tom@herbertland.com>
> Signed-off-by: Cong Wang <cong.wang@bytedance.com>
> ---
> net/kcm/kcmsock.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
> index 71899e5a5a11..661c40cdab3e 100644
> --- a/net/kcm/kcmsock.c
> +++ b/net/kcm/kcmsock.c
> @@ -1425,8 +1425,6 @@ 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;
Looks correct, but if strp_init() ever grows code which needs
to be unwound in strp_done() we'd risk a leak. This seems to
have been Tom's intent.
Could we perhaps reorder the sk_user_data check vs the strp_init() call?
sock_map already calls strp_init() under the callback lock so we'd not
be introducing any new lock ordering.
^ permalink raw reply [flat|nested] 2+ messages in thread
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