netdev - Re: [PATCH net v2 1/2] tls: handle data disappearing from under the TLS ULP

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Message-ID: <20250812062825.391c030c@kernel.org>
Date: Tue, 12 Aug 2025 06:28:25 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Paolo Abeni <pabeni@...hat.com>
Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com,
 andrew+netdev@...n.ch, horms@...nel.org, borisp@...dia.com,
 john.fastabend@...il.com, shuah@...nel.org,
 linux-kselftest@...r.kernel.org, sd@...asysnail.net, will@...lsroot.io,
 savy@...t3mfailure.io
Subject: Re: [PATCH net v2 1/2] tls: handle data disappearing from under the
 TLS ULP

On Tue, 12 Aug 2025 12:45:56 +0200 Paolo Abeni wrote:
> On 8/8/25 1:29 AM, Jakub Kicinski wrote:
> > diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
> > index 549d1ea01a72..51c98a007dda 100644
> > --- a/net/tls/tls_sw.c
> > +++ b/net/tls/tls_sw.c
> > @@ -1384,7 +1384,8 @@ tls_rx_rec_wait(struct sock *sk, struct sk_psock *psock, bool nonblock,
> >  			return sock_intr_errno(timeo);
> >  	}
> >  
> > -	tls_strp_msg_load(&ctx->strp, released);
> > +	if (unlikely(!tls_strp_msg_load(&ctx->strp, released)))
> > +		return tls_rx_rec_wait(sk, psock, nonblock, false);  
> 
> I'm probably missing something relevant, but I don't see anything
> preventing the above recursion from going very deep and cause stack
> overflow.
> 
> Perhaps something alike:
> 
> 		released = false;
> 		goto <function start>
> 
> would be safer?

It's a tail call to the same function, the compiler should do that for
us automatically. Can we not trust the compiler to be sensible? Both
clang and gcc get it right.