As first step, engineering, can you comment on if you see/reproduce this?
Can you think of a workaround?  We did so far not come up with one, if
one existed it could be used instead of having to request rhel7.9.z errata.
How complex do you think a fix would be?
Should we clone this bz to rhel8?

Seems like 
https://github.com/rsyslog/rsyslog/commit/5878ee24c7232d0f4f8655e7af6a1d456c07492f#diff-8812a601dc91036540f968b25f8042f76727172a6b5cc208c8db7dd0fbae5078
is fixed in rsyslog v8.2202.0 and later - that is quite recent, rsyslog
in rhel8 and rhel9 builds is older.

Our partner provided details regarding reproducer, they use gdb as follows:

  1. Create FIFO (Named Pipe) in/var/tmp
  # mkfifo /var/tmp/fifo


  2. Add `daemon.=debug |/var/tmp/fifo` to /etc/rsyslog.conf.
  # grep fifo /etc/rsyslog.conf
  daemon.=debug |/var/tmp/fifo


  3. Restart service
  # systemctl restart rsyslog


  4. Start gdb and set a breakpoint on writePipe
  # gdb -p $(pidof rsyslogd)
  ...
  (gdb) b writePipe
  Breakpoint 1 at 0x55df6bf4dd5a: file ompipe.c, line 181.
  (gdb) c
  Continuing.


  5. Log a message to the system log
  # logger -p 'daemon.debug' hoge


  6. Proceed to write()
  [Switching to Thread 0x7fd08ce5d700 (LWP 17026)]

  Breakpoint 1, doAction (pMsgData=0x7fd08ce5c9a0, pWrkrData=<optimized out>) at ompipe.c:335
  335             iRet = writePipe(ppString, pData);
  (gdb) s
  writePipe (pData=0x55df6e11d850, ppString=0x7fd08ce5c9a0) at ompipe.c:181
  181             if(pData->fd == -1) {
  (gdb) n
  189             iLenWritten = write(pData->fd, ppString[0], strlen((char*)ppString[0]));
  (gdb) list
  184                     if((iRetLocal != RS_RET_OK) || (pData->fd == -1))
  185                             ABORT_FINALIZE(RS_RET_SUSPENDED); /* whatever the failure was, we need to retry */
  186             }
  187
  188             /* create the message based on format specified */
  189             iLenWritten = write(pData->fd, ppString[0], strlen((char*)ppString[0]));
  190             if(iLenWritten < 0) {
  191                     const int e = errno;
  192                     /* If a named pipe is full, we suspend this action for a while */
  193                     if(e == EAGAIN)


  7. Send HUP to rsyslogd
  # pkill -HUP -x rsyslogd


  8. Exit gdb
  (gdb) detach
  Detaching from program: /usr/sbin/rsyslogd, process 17023
  [Inferior 1 (process 17023) detached]
  (gdb) q


  9. Message "Bad file descriptor" is output in /var/log/messages
  - Confirmed for RHEL7
    Mar  2 10:26:26 localhost rsyslogd: [origin software="rsyslogd" swVersion="8.24.0-55.el7" x-pid="17023" x-info="http://www.rsyslog.com"] rsyslogd was HUPed
    Mar  2 10:26:26 localhost rsyslogd: write error on pipe /var/tmp/fifo: Bad file descriptor [v8.24.0-55.el7]

  - Confirmed for RHEL8
    Mar  2 16:09:35 mori rsyslogd[244983]: [origin software="rsyslogd" swVersion="8.1911.0-3.el8" x-pid="244983" x-info="https://www.rsyslog.com"] rsyslogd was HUPed
    Mar  2 16:09:35 mori rsyslogd[244983]: write error on pipe /tmp/syslog_fifo: Bad file descriptor [v8.1911.0-3.el8]

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (rsyslog bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2022:1203