Ilya Maximets <[email protected]> writes: > 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.
ovs_assert will only evaluate (CONDITION) but not take any action if compiled with -DNDEBUG. So we will have a SIGSEGV instead of abort() in production compiled code. I guess it's 6-of-one, 1/2 dozen of the other - either is fine by me. >> >>>>> 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
