linux/net/openvswitch
Zhiling Zou 5d1c224dd9 net: openvswitch: reallocate update replies for mismatched IDs
ovs_flow_cmd_new() preallocates the optional reply skb before it takes
ovs_mutex and before it knows which existing flow will be updated.

That is normally fine because the skb is sized from the request flow
identifier.  That identifier also becomes the inserted flow's identifier.
For updates, however, a request with a UFID may miss the UFID lookup and
then fall back to the flow key lookup.  That lookup can legitimately find
an existing key-identified flow.  UFIDs are optional and the flow key is
the primary identifier.

For echoed replies, ovs_flow_cmd_fill_info() writes the matched flow's
identifier, not the request identifier used for the preallocation.  A short
request UFID can therefore leave too little room for the key identifier.
The fill can then fail with -EMSGSIZE and hit the BUG_ON(error < 0) in the
update path.

Once the update target has been resolved, reallocate the reply skb if the
matched flow needs a larger reply than the request identifier allowed.  Do
this before replacing the actions so the request can still fail cleanly if
the rare extra allocation fails.

Fixes: 74ed7ab926 ("openvswitch: Add support for unique flow IDs.")
Cc: stable@vger.kernel.org
Reported-by: Vega <vega@nebusec.ai>
Signed-off-by: Zhiling Zou <zhilinz@nebusec.ai>
Reviewed-by: Ilya Maximets <i.maximets@ovn.org>
Link: https://patch.msgid.link/f7bbd3c30ce81a39156e226b3872d73abed21d2f.1785644623.git.zhilinz@nebusec.ai
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2026-08-04 18:19:50 -07:00
..
actions.c net: openvswitch: fix skb leak on flow key update failure during ct 2026-07-29 17:42:33 -07:00
conntrack.c openvswitch: conntrack: annotate ct limit hlist traversal 2026-06-25 08:38:00 -07:00
conntrack.h net/sched: act_api: fix miss set post_ct for ovs after do conntrack in act_ct 2021-03-16 15:22:18 -07:00
datapath.c net: openvswitch: reallocate update replies for mismatched IDs 2026-08-04 18:19:50 -07:00
datapath.h openvswitch: fix GSO userspace truncation underflow 2026-07-21 10:25:25 +02:00
dp_notify.c net: replace use of system_wq with system_percpu_wq 2025-09-22 17:40:30 -07:00
drop.h net: openvswitch: add misc error drop reasons 2023-08-14 08:01:06 +01:00
flow_netlink.c net: openvswitch: reject oversized nested action attrs 2026-07-11 13:09:11 +02:00
flow_netlink.h net: openvswitch: remove never-working support for setting nsh fields 2025-11-14 18:13:24 -08:00
flow_table.c net: use get_random_u{16,32,64}() where appropriate 2026-04-09 19:27:43 -07:00
flow_table.h net: openvswitch: Annotate struct mask_array with __counted_by 2023-10-17 13:56:03 +02:00
flow.c net/openvswitch: check Ethernet header length in key_extract() 2026-08-04 13:02:17 +02:00
flow.h net: openvswitch: reduce cpu_used_mask memory 2023-02-06 22:36:29 -08:00
Kconfig sctp: use skb_crc32c() instead of __skb_checksum() 2025-05-21 15:40:16 -07:00
Makefile openvswitch: add trace points 2021-06-22 10:47:32 -07:00
meter.c net: openvswitch: fix potential UAF on meter attach failure 2026-07-30 13:20:03 +02:00
meter.h net: openvswitch: remove unnecessary linux/genetlink.h include 2024-04-01 21:44:34 -07:00
openvswitch_trace.c openvswitch: add trace points 2021-06-22 10:47:32 -07:00
openvswitch_trace.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
vport-geneve.c openvswitch: vport: fix race between tunnel creation and linking 2026-05-05 15:14:33 +02:00
vport-gre.c openvswitch: vport: fix race between tunnel creation and linking 2026-05-05 15:14:33 +02:00
vport-internal_dev.c net: rename netns_local to netns_immutable 2025-03-04 12:44:48 +01:00
vport-internal_dev.h
vport-netdev.c openvswitch: vport: fix race between linking and the device notifier 2026-05-18 16:38:45 -07:00
vport-netdev.h openvswitch: vport: fix race between tunnel creation and linking 2026-05-05 15:14:33 +02:00
vport-vxlan.c openvswitch: vport: fix race between tunnel creation and linking 2026-05-05 15:14:33 +02:00
vport.c openvswitch: fix GSO userspace truncation underflow 2026-07-21 10:25:25 +02:00
vport.h net: openvswitch: fix kernel-doc warnings in internal headers 2025-03-24 09:30:21 -07:00