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charset="utf-8" Content-ID: <463D7CE700D0C2489707958CCFD5B09A@eurprd04.prod.outlook.com> Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-OriginatorOrg: 1seal.org X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: DBBPR04MB7673.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1f14239e-ee6a-4f53-ae6f-08de8fd8e51d X-MS-Exchange-CrossTenant-originalarrivaltime: 01 Apr 2026 10:24:45.2413 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: e701d992-0f02-433e-a019-4256abe96ea1 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: X2Gvxf5bDtkNJ7vLAhD7HN+CZhEKe21asYKhw68P7OGgM93VZt+zie9fNnZmFQi0IaoY4LiUxCcyBY1p+xhJZg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: GV2PR04MB11884 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: 75da2163dbb6 ("tipc: introduce communication groups") Cc: stable@vger.kernel.org Signed-off-by: Oleh Konko --- v2: - make duplicate or stale GRP_ACK_MSG a full no-op via early return - place acked in reverse xmas tree style net/tipc/group.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/tipc/group.c b/net/tipc/group.c index e0e6227b433..14e6732624e 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 =3D msg_origport(hdr); struct tipc_member *m, *pm; u16 remitted, in_flight; + u16 acked; =20 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 =3D msg_grp_bc_acked(hdr); + acked =3D msg_grp_bc_acked(hdr); + if (less_eq(acked, m->bc_acked)) + return; + m->bc_acked =3D acked; if (--grp->bc_ackers) return; list_del_init(&m->small_win); --=20 2.50.0