On 07/11/16 04:06, Jakub Jelen wrote: > On 07/07/2016 09:07 PM, Nick Holland wrote: ... > This looks like related to the bug #1988 [1]. The mux process is holding > the stderr. Could you test it with the patch from the referenced bug > applied? > Also as I see you are using RHEL, you can contact your support to > provide a test package (we plan to fix this in RHEL7.3). > > [1] https://bugzilla.mindrot.org/show_bug.cgi?id=1988 > well, RHEL is what I reproduced the error on, the actual problem cropped up in an AIX project. Just not too easy to test AIX if you don't have power- hungry, outrageously expensive hw on hand. :-/ So. I loaded up a CentOS 7.2 VM, downloaded the most recent OpenSSH-portable tar file (openssh-7.2p2.tar.gz), added zlib-devel and openssl-devel, ./configure, make, make install'd the program. pkill'ed sshd, /usr/local/sbin/sshd to start sshd....and same results. I then applied this patch: diff --git a/log.c b/log.c index a5ba22f..9011f9d 100644 --- a/log.c +++ b/log.c @@ -308,7 +308,7 @@ log_change_level(LogLevel new_log_level) int log_is_on_stderr(void) { - return log_on_stderr; + return log_on_stderr && log_stderr_fd == STDERR_FILENO; } /* redirect what would usually get written to stderr to specified file */ diff --git a/ssh.c b/ssh.c index ec8a515..65e0217 100644 --- a/ssh.c +++ b/ssh.c @@ -1346,7 +1346,7 @@ static void control_persist_detach(void) { pid_t pid; - int devnull; + int devnull, keep_stderr; debug("%s: backgrounding master process", __func__); @@ -1377,8 +1377,10 @@ control_persist_detach(void) error("%s: open(\"/dev/null\"): %s", __func__, strerror(errno)); } else { + keep_stderr = log_is_on_stderr() && debug_flag; if (dup2(devnull, STDIN_FILENO) == -1 || - dup2(devnull, STDOUT_FILENO) == -1) + dup2(devnull, STDOUT_FILENO) == -1 || + (!keep_stderr && dup2(devnull, STDERR_FILENO) == -1)) error("%s: dup2: %s", __func__, strerror(errno)); if (devnull > STDERR_FILENO) close(devnull); and seems to work, at least once I modified my script to use the sftp I had compiled in /usr/local/bin rather than the "factory" /usr/bin (oops). my test script: ==== #!/bin/bash mkdir -p ~/dest for X in 1 2 3 4 5 6 7 8 9 10; do echo $X echo "cd dest put $0" | /usr/local/bin/sftp -b - localhost 2>&1 | tee -a outfile done ==== So yes, looks like there's a fix on the way. Thanks! Nick. _______________________________________________ openssh-unix-dev mailing list openssh-unix-dev@xxxxxxxxxxx https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
