Bug 3310

Summary: Correctly restoring channel's FDs nonblocking mode
Product: Portable OpenSSH Reporter: Dmitry Belyavskiy <dbelyavs>
Component: sshAssignee: Assigned to nobody <unassigned-bugs>
Status: CLOSED DUPLICATE    
Severity: normal CC: djm
Priority: P5    
Version: 8.6p1   
Hardware: Other   
OS: Linux   

Description Dmitry Belyavskiy 2021-05-11 17:55:34 AEST 
OpenSSH incorrectly restores the standard mode (blocking mode) on standard output upon exiting. This causes the next shell scripts commands to potentially fail in EAGAIN.
The reproducer is:

#!/bin/sh
(
ssh localhost true
cat /dev/zero
) | sleep 30

Restoring the blocking modes happens with the duped file descriptors and too late.

The changes causing this problem was introduced in 4d5456c

The PR intended to fix the issue is https://github.com/openssh/openssh-portable/pull/246
Comment 1 Damien Miller 2021-05-19 11:19:41 AEST 

*** This bug has been marked as a duplicate of bug 3280 ***
Comment 2 Damien Miller 2022-02-25 13:57:59 AEDT 
closing bugs resolved before openssh-8.9