Re: [PATCH net] strparser: make sure __strp_recv isn't running before tearing down the parser

[Jiayuan Chen <jiayuan.chen@linux.dev>]

On 9/25/26 9:51 PM, Sabrina Dubroca wrote:
> The comment above strp_done() claims that if strp is stopped,
> strp_recv will no longer be called. That's only true if the caller has
> a mechanism (eg locking) to guarantee that strp_recv() calls that
> started before strp_stop() have completed by the time we call
> strp_done().
>
> This adds a lock_sock/release_sock pair to guarantee that any
> in-flight strp_recv() (which runs under either bh_lock_sock or
> lock_sock, depending if it's called from ->sk_data_ready or strp_work)
> has completed.
>
> Only espintcp can be affected by this race condition, but this patch
> makes sure no future user of strp can have the bug.
>
> Reported-by: Hyunwoo Kim <imv4bel@gmail.com>
> Link: https://lore.kernel.org/all/aZgpkyTDU3aXe_V0@v4bel/
> Fixes: e27cca96cd68 ("xfrm: add espintcp (RFC 8229)")
> Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
> ---
> This could crash on strp->sk ("general mode" of strp), but this mode
> has been here for 9 years and has never been used. I'll send a
> net-next patch to get rid of it.
>
>   net/strparser/strparser.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/net/strparser/strparser.c b/net/strparser/strparser.c
> index a23f4b4dfc67..401e67533005 100644
> --- a/net/strparser/strparser.c
> +++ b/net/strparser/strparser.c
> @@ -511,6 +511,10 @@ void strp_done(struct strparser *strp)
>   {
>   	WARN_ON(!strp->stopped);
>   
> +	lock_sock(strp->sk);
> +	/* sync with pending strp_recv */
> +	release_sock(strp->sk);
> +


Using sk directly inside strparser breaks the abstraction and that's why 
cb exists.

We can totally use it instead
     strp->cb.lock(strp);
     strp->cb.unlock(strp);


>   	cancel_delayed_work_sync(&strp->msg_timer_work);
>   	cancel_work_sync(&strp->work);
>