diff options
| author | Oleh Konko <security@1seal.org> | 2026-04-02 09:48:57 +0000 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-04-03 15:31:17 -0700 |
| commit | 48a5fe38772b6f039522469ee6131a67838221a8 (patch) | |
| tree | 0617de2737d4a04c29e0dedbf9cc0d09140746f8 | |
| parent | 7b735ef81286007794a227ce2539419479c02a5f (diff) | |
tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG
The GRP_ACK_MSG handler in tipc_group_proto_rcv() currently decrements
bc_ackers on every inbound group ACK, even when the same member has
already acknowledged the current broadcast round.
Because bc_ackers is a u16, a duplicate ACK received after the last
legitimate ACK wraps the counter to 65535. Once wrapped,
tipc_group_bc_cong() keeps reporting congestion and later group
broadcasts on the affected socket stay blocked until the group is
recreated.
Fix this by ignoring duplicate or stale ACKs before touching bc_acked or
bc_ackers. This makes repeated GRP_ACK_MSG handling idempotent and
prevents the underflow path.
Fixes: 2f487712b893 ("tipc: guarantee that group broadcast doesn't bypass group unicast")
Cc: stable@vger.kernel.org
Signed-off-by: Oleh Konko <security@1seal.org>
Reviewed-by: Tung Nguyen <tung.quang.nguyen@est.tech>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/41a4833f368641218e444fdcff822039.security@1seal.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/tipc/group.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/net/tipc/group.c b/net/tipc/group.c index e0e6227b433b..14e6732624e2 100644 --- a/net/tipc/group.c +++ b/net/tipc/group.c @@ -746,6 +746,7 @@ void tipc_group_proto_rcv(struct tipc_group *grp, bool *usr_wakeup, u32 port = msg_origport(hdr); struct tipc_member *m, *pm; u16 remitted, in_flight; + u16 acked; if (!grp) return; @@ -798,7 +799,10 @@ void tipc_group_proto_rcv(struct tipc_group *grp, bool *usr_wakeup, case GRP_ACK_MSG: if (!m) return; - m->bc_acked = msg_grp_bc_acked(hdr); + acked = msg_grp_bc_acked(hdr); + if (less_eq(acked, m->bc_acked)) + return; + m->bc_acked = acked; if (--grp->bc_ackers) return; list_del_init(&m->small_win); |