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.

The xt action is in a very bad shape. Here's a few things which cause trouble (tested on a vanilla kernel):

# tc filter add dev d0 parent ffff: u32 match u32 0 0 action xt -j DROP
tablename: mangle hook: NF_IP_PRE_ROUTING
Segmentation fault (core dumped)

# tc filter add dev d0 parent ffff: u32 match u32 0 0 \
        action xt -j MARK --set-mark 0x1 \
        action xt -j MARK --set-mark 0x1
tablename: mangle hook: NF_IP_PRE_ROUTING
 	target:  MARK set 0x1 index 0
Segmentation fault (core dumped)

At least adding two separate matches with xt action as reported in bug 1314403 works.

Patches sent upstream: https://www.mail-archive.com/netdev@vger.kernel.org/msg114055.html

These are the patches to backport (at least):

445745221a21e tc: m_xt: Prevent segfault with standard targets
8eee75a8358c5 tc: m_xt: Fix segfault when adding multiple actions at once
f1a7c7d8301e9 tc: m_xt: Fix indenting
b45f9141c2602 tc: m_xt: Get rid of one indentation level in parse_ipt()
b0ba0185763ad tc: m_xt: Drop unused variable fw in parse_ipt()
ab8f52fc4ae11 tc: m_xt: Get rid of rargc in parse_ipt()
28432f370e6ad tc: m_xt: Get rid of iargc variable in parse_ipt()
f6ddd9c5da4e5 tc: m_xt: Simplify argc adjusting in parse_ipt()
2ef4008585ec9 tc: m_xt: Introduce get_xtables_target_opts()
4b83a08c280fc m_xt: whitespace cleanup

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, 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-2017:2171