On 4/6/22 16:53, Aaron Conole wrote: > Dumitru Ceara <[email protected]> writes: > >> On 4/5/22 21:20, Aaron Conole wrote: >>> Dumitru Ceara <[email protected]> writes: >>> >>>> On 4/5/22 16:41, Aaron Conole wrote: >>>>> Dumitru Ceara <[email protected]> writes: >>>>> >>>>>> This is undefined behavior and was reported by UB Sanitizer: >>>>>> lib/meta-flow.c:3445:16: runtime error: member access within null >>>>>> pointer of type 'struct vl_mf_field' >>>>>> #0 0x6aad0f in mf_get_vl_mff lib/meta-flow.c:3445 >>>>>> #1 0x6d96d7 in mf_from_oxm_header lib/nx-match.c:260 >>>>>> #2 0x6d9e2e in nx_pull_header__ lib/nx-match.c:341 >>>>>> #3 0x6daafa in nx_pull_header lib/nx-match.c:488 >>>>>> #4 0x6abcb6 in mf_vl_mff_nx_pull_header lib/meta-flow.c:3605 >>>>>> #5 0x73b9be in decode_NXAST_RAW_REG_MOVE lib/ofp-actions.c:2652 >>>>>> #6 0x764ccd in ofpact_decode lib/ofp-actions.inc2:4681 >>>>>> [...] >>>>>> lib/sset.c:315:12: runtime error: applying zero offset to null pointer >>>>>> #0 0xcc2e6a in sset_at_position /root/ovs/lib/sset.c:315:12 >>>>>> #1 0x5734b3 in port_dump_next >>>>>> /root/ovs/ofproto/ofproto-dpif.c:4083:20 >>>>>> [...] >>>>>> lib/ovsdb-data.c:2194:56: runtime error: applying zero offset to null >>>>>> pointer >>>>>> #0 0x5e9530 in ovsdb_datum_added_removed >>>>>> /root/ovs/lib/ovsdb-data.c:2194:56 >>>>>> #1 0x4d6258 in update_row_ref_count >>>>>> /root/ovs/ovsdb/transaction.c:335:17 >>>>>> #2 0x4c360b in for_each_txn_row >>>>>> /root/ovs/ovsdb/transaction.c:1572:33 >>>>>> [...] >>>>>> lib/ofpbuf.c:440:30: runtime error: applying zero offset to null >>>>>> pointer >>>>>> #0 0x75066d in ofpbuf_push_uninit lib/ofpbuf.c:440 >>>>>> #1 0x46ac8a in ovnacts_parse lib/actions.c:4190 >>>>>> #2 0x46ad91 in ovnacts_parse_string lib/actions.c:4208 >>>>>> #3 0x4106d1 in test_parse_actions tests/test-ovn.c:1324 >>>>>> [...] >>>>>> lib/ofp-actions.c:3205:22: runtime error: applying non-zero offset 2 >>>>>> to null pointer >>>>>> #0 0x6e1641 in set_field_split_str >>>>>> /root/ovs/lib/ofp-actions.c:3205:22 >>>>>> [...] >>>>>> lib/tnl-ports.c:74:12: runtime error: applying zero offset to null >>>>>> pointer >>>>>> #0 0xceffe7 in tnl_port_cast /root/ovs/lib/tnl-ports.c:74:12 >>>>>> #1 0xcf14c3 in map_insert /root/ovs/lib/tnl-ports.c:116:13 >>>>>> [...] >>>>>> ofproto/ofproto.c:8905:16: runtime error: applying zero offset to null >>>>>> pointer >>>>>> #0 0x556795 in eviction_group_hash_rule >>>>>> /root/ovs/ofproto/ofproto.c:8905:16 >>>>>> #1 0x503f8d in eviction_group_add_rule >>>>>> /root/ovs/ofproto/ofproto.c:9022:42 >>>>>> [...] >>>>>> >>>>>> Also, it's valid to have an empty ofpact list and we should be able to >>>>>> try to iterate through it. >>>>>> >>>>>> UB Sanitizer report: >>>>>> include/openvswitch/ofp-actions.h:222:12: runtime error: applying zero >>>>>> offset to null pointer >>>>>> #0 0x665d69 in ofpact_end >>>>>> /root/ovs/./include/openvswitch/ofp-actions.h:222:12 >>>>>> #1 0x66b2cf in ofpacts_put_openflow_actions >>>>>> /root/ovs/lib/ofp-actions.c:8861:5 >>>>>> #2 0x6ffdd1 in ofputil_encode_flow_mod >>>>>> /root/ovs/lib/ofp-flow.c:447:9 >>>>>> [...] >>>>>> >>>>>> Signed-off-by: Dumitru Ceara <[email protected]> >>>>>> --- >>>>>> v5: >>>>>> - Rebase. >>>>>> v4: >>>>>> - Addressed Ilya's comments. >>>>>> --- >>>>> >>>>> Glad to see that the undefined behavior got removed, BUT this >>>>> can introduce some different undefined behavior - places where we >>>>> have a calls to ofpbuf_at_...() always assume a valid pointer is >>>>> returned. >>>>> >>>> >>>> Thanks for the review! >>>> >>>>> I think it makes sense to abort if b->data is NULL in these cases. >>>>> Maybe something like: >>>>> >>>>> ovs_abort(0, "invalid buffer data pointer"); >>>>> >>>>> WDYT? >>>>> >>>> >>>> Calling ovs_abort() directly from openvswitch/util.h will be a challenge >>>> because it's an internal function and the openvswitch/util.h header is >>>> public. Worst case we just call ovs_assert() like we already do in >>>> ofpbuf_at_assert(). >>> >>> Maybe we can expose ovs_abort as well? >>> >> >> We can, but should we then expose all of the following, for consistency? >> >> OVS_NO_RETURN void ovs_abort(int err_no, const char *format, ...) >> OVS_PRINTF_FORMAT(2, 3); >> OVS_NO_RETURN void ovs_abort_valist(int err_no, const char *format, va_list) >> OVS_PRINTF_FORMAT(2, 0); >> OVS_NO_RETURN void ovs_fatal(int err_no, const char *format, ...) >> OVS_PRINTF_FORMAT(2, 3); >> OVS_NO_RETURN void ovs_fatal_valist(int err_no, const char *format, va_list) >> OVS_PRINTF_FORMAT(2, 0); > > I think it makes sense. Maybe Ilya/Ian disagrees
Hmm. Can we just use ovs_assert() instead of ovs_abort() ? This one is defined in the openvswitch/util.h. > >>>> But, just to make sure I understood properly, you'd like to assert that >>>> b->data is not NULL only in ofpbuf_at() and ofpbuf_at_assert(), right? >>> >>> right - only for those places where we have the assumption that the >>> return must be !NULL >>> >> >> Ok. >> >>>> Because the other ofpact_...() functions are also called in valid >>>> scenarios on ofpbufs that have b->data = NULL. >>>> >> >> [...] > _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
