From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B389C2765C4; Mon, 13 Apr 2026 16:07:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776096478; cv=none; b=Mp0e/X3aqCHZ997jBg/87/YCoUMWO/h7GTSh44NoA270rj2wWFQNfMbAuu7XXGVJcUeKZcmb6gUTLChp4WrO5j6ar6o1vhnC5/jqf/8AMMMyEbVPg7MeMIdRZmkH+D0AOlJU72T7GVJau/MyvgCihnsq39nSNp5RiltVNBN4SoU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776096478; c=relaxed/simple; bh=EnJxIZwPUrcVVFWnU8FXaeSd8A7jAoudptN9jLqS9mQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=AilI41NjMendJoHopglRrsHRuXwypJCBZGvznbyxsU3AbAADMu62V8Hhyv8mrN6d3nlaEDSSL5IWplmHZok16bhSOBqFqixyQ9ua/LEEcrNjrTYiEEWnK12TzMUqNRrBM2alUz5KMOrl2Zt9TvpAjAgm+W0yFL47ynzxaOPBrK0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=VqSfoCSJ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="VqSfoCSJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 951CDC2BCAF; Mon, 13 Apr 2026 16:07:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776096477; bh=EnJxIZwPUrcVVFWnU8FXaeSd8A7jAoudptN9jLqS9mQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VqSfoCSJ+Yx72lFFpCpoAuS+doBn5LXlZbR5CDR+Gl2FO7BAaErN7n49rs8zZHXzL gIghHcHyx6qKRzfi3aGHxoDg3rjYauJ2DJ33J59cpURr/Ss5qwK6laHm8edXF7sbiB BKtr9YJd4FjK6xPmwcKmXFNEgSqTY1fUqeq/e0D0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Oleh Konko , Tung Nguyen , Simon Horman , Jakub Kicinski Subject: [PATCH 6.18 26/83] tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG Date: Mon, 13 Apr 2026 17:59:54 +0200 Message-ID: <20260413155731.996984320@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260413155731.019638460@linuxfoundation.org> References: <20260413155731.019638460@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Oleh Konko commit 48a5fe38772b6f039522469ee6131a67838221a8 upstream. 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 Reviewed-by: Tung Nguyen Reviewed-by: Simon Horman Link: https://patch.msgid.link/41a4833f368641218e444fdcff822039.security@1seal.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/tipc/group.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/net/tipc/group.c +++ b/net/tipc/group.c @@ -746,6 +746,7 @@ void tipc_group_proto_rcv(struct tipc_gr 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_gr 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);