RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

Created attachment 1070038 [details]
ksh-20120801-F_dupfd_cloexec.patch

I do not yet have a reproducer, but have a patch
that handles the final state, and user reports
the patch corrects this specific crash condition.

  But I am afraid it is just hiding a descriptor
leak. In the crash coredump, it had:

(gdb) p shp->gd->lim.open_max
$1 = 64
(gdb) p fd
$2 = 122

Any luck with getting a reproducer?

I am able to reproduce a file descriptor leak with this code :

while true; do
    foo=`pvs << EOF
         $(pvs)
         EOF`
done

however patch from comment 0 does not fix it, so it may be unrelated.

The patch in comment 0 just attempts to do "what was meant", and  (mostly)
match latest ast code, that is to use F_DUPFD_CLOEXEC, detected by build
configure, that sets the value of F_dupfd_cloexec.
I believe the patch has the side effect of not "exporting" the leak in
ksh internal structures to forked shells, thus making it harder to have
cumulative leaks, that end in out of bounds writes.