openssh unix dev - Jun 2025 - [PATCH] mux: fix incorrect return value check in local forward cancellation

Hi,

This patch fixes a logic error in mux_master_process_close_fwd().

channel_cancel_lport_listener() returns 1 on success and 0 on failure.
The previous code incorrectly checked for `== -1`, a value the function
never returns, so failure was not detected and the "port not found"
error message was never shown when cancelling dynamic or local port
forwards.

The patch applies cleanly to current master and all GitHub CI jobs are
green (see mirror PR):
   https://github.com/openssh/openssh-portable/pull/577

If merged, could you please keep the author line
    From: Boris Tonofa <b.tonofa at ideco.ru>
in the commit message?  My company would appreciate the attribution.

Thanks for your time and review.

Best regards,
Boris


 From 41aacbdbf107bebae150a46bd098d4ed1f379019 Mon Sep 17 00:00:00 2001
From: Boris Tonofa <b.tonofa at ideco.ru>
Date: Fri, 20 Jun 2025 19:22:14 +0300
Subject: [PATCH] mux: fix incorrect return value check in local forward
  cancellation

channel_cancel_lport_listener() returns 1 on success and 0 on failure.
The previous code incorrectly checked for `== -1`, a value the function
never returns, so failure was not detected and the "port not found"
error message was never shown when cancelling dynamic or local port
forwards.
---
  mux.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mux.c b/mux.c
index 415024f74..ad40b4489 100644
--- a/mux.c
+++ b/mux.c
@@ -931,7 +931,7 @@ mux_master_process_close_fwd(struct ssh *ssh, u_int rid,
  	} else {	/* local and dynamic forwards */
  		/* Ditto */
  		if (channel_cancel_lport_listener(ssh, &fwd, fwd.connect_port,
-		    &options.fwd_opts) == -1)
+		    &options.fwd_opts) != 1)
  			error_reason = "port not found";
  	}

-- 
2.47.0

On Fri, 20 Jun 2025, Boris Tonofa wrote:
> Hi,
> 
> This patch fixes a logic error in mux_master_process_close_fwd().
> 
> channel_cancel_lport_listener() returns 1 on success and 0 on failure.
> The previous code incorrectly checked for `== -1`, a value the function
> never returns, so failure was not detected and the "port not
found"
> error message was never shown when cancelling dynamic or local port
> forwards.
> 
> The patch applies cleanly to current master and all GitHub CI jobs are
> green (see mirror PR):
>   https://github.com/openssh/openssh-portable/pull/577
> 
> If merged, could you please keep the author line
>    From: Boris Tonofa <b.tonofa at ideco.ru>
> in the commit message?  My company would appreciate the attribution.
Thanks for the fix, here's what I committed:

Author: djm at openbsd.org <djm at openbsd.org>
Date:   Fri Jul 4 00:17:55 2025 +0000

    upstream: mux: fix incorrect return value check in local forward
    
    cancellation
    
    channel_cancel_lport_listener() returns 1 on success and 0 on failure.
    The previous code incorrectly checked for `== -1`, a value the function
    never returns, so failure was not detected and the "port not
found"
    error message was never shown when cancelling dynamic or local port
    forwards.
    
    From: Boris Tonofa <b.tonofa at ideco.ru>
    
    OpenBSD-Commit-ID: 3e9d2252a4d0bd318d4f25e2b518afb44acea170


Hope this is okay.

-d