From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 D1B653B811F; Mon, 17 Aug 2026 14:07:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786975623; cv=none; b=s/GX9tlzlizz7uQa+1mGZN7FQh59Ls4djnuOOXNDJgPIfg+ZGQeoZoLssFrdP0IBz7IX4hUnvzhv//zpZ1UVtRJyStn37BVediCGcKUa4fSRnseGSE3/GZ1SPZLP7lKs9GCWs+DRe0gOMCA11hTfiBMRqTInwe2xCbiYS1nCuyw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786975623; c=relaxed/simple; bh=xrFcLJ0mnAjgnRi8vhgIdO4vdnrtqdIjxVvgV46sBx4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jdYQGgLr+Mgd4hdQHBlVnYOezOoq7Bc6fwoc/rLaLixzUFFy0MoIZFPajri9k+IhXkJ4Aqg8bXAMCbCBbyW5q4UmbNQz45xz/e9j9MmV3A6/uwCYpbXNLXjuYnbAB0P93W7KyezMwBGHQEWFbNlIDtZdseRxC9ev7zSWeBz0hYI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=EJRWBJNf; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="EJRWBJNf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39BCD1F00A3A; Mon, 17 Aug 2026 14:07:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786975621; bh=v5N6ZFZ8DSlMaaNjOGPHHDZdPFsITTKcHUmtvzxwFq0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=EJRWBJNfNwMYibRL2gwsToEV67JgcoKifQbuzMijaYRo1NMMxO1Nq9TpK3mNfXmkp ysX+sEuMpJek081H9jLrHMB003nEkNj6kt+urx8W+utyo3RJTMsBnxtsoCTPp5aIV7 XttKmw2QVKjlrKaDSuE/YSSIeJk37hiwdwAUDPIU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, AutonomousCodeSecurity@microsoft.com, Vadim Fedorenko , "Cen Zhang (Microsoft)" , Simon Horman , Paolo Abeni , Sasha Levin Subject: [PATCH 5.10 091/389] tipc: fix u16 MTU truncation in media and bearer MTU validation Date: Mon, 17 Aug 2026 15:28:50 +0200 Message-ID: <20260817132542.657975689@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132538.796021292@linuxfoundation.org> References: <20260817132538.796021292@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 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Cen Zhang (Microsoft) [ Upstream commit 9f29cd8a8e7901a2617c8064ce9f50fc67b97cb8 ] Both TIPC_NL_MEDIA_SET and TIPC_NL_BEARER_SET accept user-supplied MTU values but only enforce a minimum bound, not a maximum. When a user sets the MTU to a value exceeding U16_MAX (65535), it passes validation but is silently truncated when assigned to u16 fields l->mtu and l->advertised_mtu in tipc_link_create(). Values like 65536 (0x10000) truncate to 0, causing a division by zero in tipc_link_set_queue_limits() which computes TIPC_MAX_PUBL / (l->mtu / ITEM_SIZE). Other overflowing values (e.g. 65537-131071) produce small incorrect MTU values, resulting in link malfunction behaviors. Crash stack (triggered as unprivileged user via user namespace): tipc_link_set_queue_limits net/tipc/link.c:2531 tipc_link_create net/tipc/link.c:520 tipc_node_check_dest net/tipc/node.c:1279 tipc_disc_rcv net/tipc/discover.c:252 tipc_rcv net/tipc/node.c:2129 tipc_udp_recv net/tipc/udp_media.c:392 Two independent paths lack the upper bound check: 1. tipc_udp_mtu_bad() -- called from __tipc_nl_media_set() (MEDIA_SET) 2. inline check in __tipc_nl_bearer_set() at bearer.c:1160 (BEARER_SET) Fix both by rejecting MTU values above U16_MAX. Fixes: 901271e0403a ("tipc: implement configuration of UDP media MTU") Reported-by: AutonomousCodeSecurity@microsoft.com Closes: https://lore.kernel.org/all/CAB8m9WgETt0AjmFwE=F-CKjGXsK6_WDv0=kbYRcC8-noo+amnA@mail.gmail.com Reviewed-by: Vadim Fedorenko Signed-off-by: Cen Zhang (Microsoft) Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260714041541.307702-1-blbllhy@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- net/tipc/netlink.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/net/tipc/netlink.c +++ b/net/tipc/netlink.c @@ -113,12 +113,16 @@ const struct nla_policy tipc_nl_node_pol }; /* Properties valid for media, bearer and link */ +static struct netlink_range_validation tipc_nl_mtu_range = { + .max = U16_MAX, +}; + const struct nla_policy tipc_nl_prop_policy[TIPC_NLA_PROP_MAX + 1] = { [TIPC_NLA_PROP_UNSPEC] = { .type = NLA_UNSPEC }, [TIPC_NLA_PROP_PRIO] = { .type = NLA_U32 }, [TIPC_NLA_PROP_TOL] = { .type = NLA_U32 }, [TIPC_NLA_PROP_WIN] = { .type = NLA_U32 }, - [TIPC_NLA_PROP_MTU] = { .type = NLA_U32 }, + [TIPC_NLA_PROP_MTU] = NLA_POLICY_FULL_RANGE(NLA_U32, &tipc_nl_mtu_range), [TIPC_NLA_PROP_BROADCAST] = { .type = NLA_U32 }, [TIPC_NLA_PROP_BROADCAST_RATIO] = { .type = NLA_U32 } };