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 4EC573090F5; Mon, 13 Apr 2026 16:40:45 +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=1776098445; cv=none; b=TIOdQAnQsMZmob/dwb+Ek6i60L0x4zbJm9dST/N3t8u8g094R6DVFkqT8vRNQP6suM6LbKlHmWd0dY9JLdRUKxqgnpVar/bFUwk2b0NIfA2pQvoKYFA6EUHcmP8Qaeiuc5DzMClj9WHW8qyETmBaryzvzHfmYCXOUHF8pXHPffo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776098445; c=relaxed/simple; bh=Qbm9TkEorcZqdicF3D0OthaE9e2MuvGSqYrKwStbN4Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MIG7ThzdKcQbvW9woXCEYmVNLAzeiNgohy0knCbNr2atW2Ko8odsgJDIdVhW8A5HiWKRqUk/1i8omBFD1cfay9wL4swM1nxvBPpbGfPUkt4gGWN1mcG2OxFVbA8mZZWpDD9rY/u0bbZMbGfPRNFaWydV2H2pRHeVpF/On7DxAng= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=h4scTGQ6; 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="h4scTGQ6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D66F8C2BCAF; Mon, 13 Apr 2026 16:40:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776098445; bh=Qbm9TkEorcZqdicF3D0OthaE9e2MuvGSqYrKwStbN4Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=h4scTGQ6Qv9S0I+h3EOrxq0WUxDsyUBThImY8xjv24IZblIyzSqk72q7QFN5QU/0J 86S4vcf5/V3K0e6T7TNFHZCsA0h8Ak/75mWTtoP+JdLTbW7TLyu7zYiNRB2OrxQk6I H3xisvB9pXQJvy/c62FJC8T/heRG8KHyE5/22Ngw= 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 5.15 527/570] tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG Date: Mon, 13 Apr 2026 18:00:58 +0200 Message-ID: <20260413155850.190543552@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260413155830.386096114@linuxfoundation.org> References: <20260413155830.386096114@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 5.15-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);