[PATCH v2 1/2] ipvs: do not propagate one-packet flag to synced conns

From: Zhiling Zou <[email protected]>

Synced connections can be created before their destination exists. When
the destination is later added, ip_vs_bind_dest() copies connection flags
from the destination into cp->flags.

IP_VS_CONN_F_ONE_PACKET connections are not synced. If a synced
connection inherits IP_VS_CONN_F_ONE_PACKET while it is already hashed,
expiry can treat it as a one-packet connection and skip unlinking the
existing conn_tab node, leaving stale hash nodes pointing at a freed
struct ip_vs_conn.

Drop IP_VS_CONN_F_ONE_PACKET from destination flags when binding synced
connections.

Fixes: 26ec037f9841 ("IPVS: one-packet scheduling")
Cc: [email protected]
Reported-by: Yuan Tan <[email protected]>
Reported-by: Yifan Wu <[email protected]>
Reported-by: Juefei Pu <[email protected]>
Reported-by: Xin Liu <[email protected]>
Suggested-by: Julian Anastasov <[email protected]>
Signed-off-by: Zhiling Zou <[email protected]>
Signed-off-by: Ren Wei <[email protected]>
---
Changes in v2:
- Replace the v1 approach that preserved hash-related flags on late
  destination binding.
- Drop IP_VS_CONN_F_ONE_PACKET from conn_flags for synced connections,
  because one-packet connections are not synchronized.
- Leave forwarding method updates to the follow-up hn1 hashing fix in
  patch 2.
- Add Suggested-by for Julian's review suggestion.

v1 Link: https://lore.kernel.org/all/1b914f41d725bc064c9ba9830dc8169329737270.1782540466.git.roxy520tt@gmail.com/

 net/netfilter/ipvs/ip_vs_conn.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c
index 6ed2622363f0..0682cec5f0a7 100644
--- a/net/netfilter/ipvs/ip_vs_conn.c
+++ b/net/netfilter/ipvs/ip_vs_conn.c
@@ -1014,6 +1014,9 @@ ip_vs_bind_dest(struct ip_vs_conn *cp, struct ip_vs_dest *dest)
 	flags = cp->flags;
 	/* Bind with the destination and its corresponding transmitter */
 	if (flags & IP_VS_CONN_F_SYNC) {
+		/* Synced conns are hashed, so they can not get this flag */
+		conn_flags &= ~IP_VS_CONN_F_ONE_PACKET;
+
 		/* if the connection is not template and is created
 		 * by sync, preserve the activity flag.
 		 */
-- 
2.43.0