On Mon, Jan 5, 2026 at 12:53 PM Ilya Maximets <[email protected]> wrote:

> On 1/5/26 11:02 AM, Ales Musil via dev wrote:
> > The nexthop of Logical Router Policy can be NULL or empty, make sure
> > the northd doesn't crash when that happens:
>
> Hi, Ales.  Not a full review, but see a few comments below.
>

Hi Ilya,
thank you for the review.


>
> The patch subject, IMO, is too generic and can't be used to find the
> issue in the git history.  Should be something like
> "northd: Fix crash on explicit output-port reroute without nexthop".
> Or something like this.
>

That's fair, updated.


>
> >
> > northd/northd.c:14771:39: runtime error: null pointer passed as argument
> 1, which is declared to never be null
>
> bit: This line can be wrapped.
>

> > string.h:247:33: note: nonnull attribute specified here
> >     build_route_policies northd/northd.c:14771:32
> >     en_route_policies_run northd/en-northd.c:324:9
> >     engine_recompute lib/inc-proc-eng.c:448:33
> >     engine_compute lib/inc-proc-eng.c:491:17
> >     engine_run_node lib/inc-proc-eng.c:550:14
> >     engine_run ovn/lib/inc-proc-eng.c:579:9
> >     inc_proc_northd_run northd/inc-proc-northd.c:608:5
> >     main northd/ovn-northd.c:1134:36
> >
> > Reported-at: https://issues.redhat.com/browse/FDP-2919
> > Signed-off-by: Ales Musil <[email protected]>
> > ---
> >  northd/northd.c     |  5 +++++
> >  tests/ovn-northd.at | 28 ++++++++++++++++++++++++++++
> >  2 files changed, 33 insertions(+)
> >
> > diff --git a/northd/northd.c b/northd/northd.c
> > index c3c0780a3..2faf5d09a 100644
> > --- a/northd/northd.c
> > +++ b/northd/northd.c
> > @@ -14762,6 +14762,11 @@ build_route_policies(struct ovn_datapath *od,
> const struct hmap *lr_ports,
> >              for (size_t j = 0; j < n_nexthops; j++) {
> >                  char *nexthop = rule->n_nexthops
> >                      ? rule->nexthops[j] : rule->nexthop;
> > +
> > +                if (!nexthop || !nexthop[0]) {
>
> I'm a little confused, how the nexthop can be NULL here?  The default
> database value for a string is an empty string, which is not supposed
> to be NULL.  And if n_nexthops is not zero, then we must have the
> rule->nexthops[j] non-NULL.  What am I missing here?
>

Both nexthop and nexthops columns are defined as "min": 0,
so please correct if I'm wrong, but that means it can also be NULL,
right?


>
> > +                    continue;
> > +                }
> > +
> >                  struct ovn_port *out_port = NULL;
> >                  bool is_ipv4 = strchr(nexthop, '.') ? true : false;
> >
> > diff --git a/tests/ovn-northd.at b/tests/ovn-northd.at
> > index 5b1a8b6f8..79075465b 100644
> > --- a/tests/ovn-northd.at
> > +++ b/tests/ovn-northd.at
> > @@ -19030,3 +19030,31 @@ check ovn-nbctl --wait=sb sync
> >  OVN_CLEANUP_NORTHD
> >  AT_CLEANUP
> >  ])
> > +
> > +OVN_FOR_EACH_NORTHD_NO_HV([
> > +AT_SETUP([Router policies - crash])
>
> This test name also doesn't provide any useful information about the test.
>
> > +ovn_start
> > +
> > +dnl Test with a simple reroute policy with an explicit output-port set.
>
> This comment should be converted into the test name, IMO.  E.g.:
>
> AT_SETUP([Router policies - explicit output-port without nexthop])
>

> > +check ovn-nbctl
>   \
> > +    -- lr-add lr0
>   \
> > +    -- lrp-add lr0 lrp1 00:00:00:00:00:01 1.1.1.1/24
>    \
> > +    -- lrp-add lr0 lrp2 00:00:00:00:00:02 2.2.2.1/24
>    \
> > +    -- --output-port=lrp2 lr-policy-add lr0 100 "ip4.src ==
> 42.42.42.42" \
> > +                                        reroute 3.3.3.3
> > +
> > +dnl Clear the nexthops. This shouldn't crash and not produce any lflows.
>
> s/and not/or/ ?
>
> > +uuid=$(fetch_column nb:logical_router_policy _uuid priority=100)
> > +check ovn-nbctl clear logical_router_policy $uuid nexthops
> > +check ovn-nbctl --wait=sb sync
> > +
> > +ovn-sbctl dump-flows lr0 > lr0flows
>
> nit: Can be wrapped in AT_CHECK.
>
> > +AT_CAPTURE_FILE([lr0flows])
> > +
> > +AT_CHECK([grep "lr_in_policy[[^_]]" lr0flows | ovn_strip_lflows |
> sort], [0], [dnl
> > +  table=??(lr_in_policy       ), priority=0    , match=(1),
> action=(reg8[[0..15]] = 0; next;)
> > +])
> > +
> > +OVN_CLEANUP_NORTHD
> > +AT_CLEANUP
> > +])
>
>
All nits will be addressed in v2.

Regards,
Ales
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