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 738EE346769; Thu, 2 Jul 2026 16:28:06 +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=1783009688; cv=none; b=VMMQ5ixaMLpUgiS8rFZUSzffZt6DYpeitmz7VUfiPARLcMEO0w8VKrlMPwDemcPIpczbvX1xgMwS2SC8NRlLWCsC8HVa2UBNZhBO7ZQgcH5BHZwmHlVxZU/qvOXDTIEUTXNKzcZumTUd6dtaM3KWSjXIfjFAvLOx9KEibMHIpNI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783009688; c=relaxed/simple; bh=MEZ0bv3UK3u6q0YqC0Sj7RXEsb31Ya30ojimth/9Y94=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HXIxZZE/S9E7UNLRgeusTesWc/G3m+xwYEHcuyFysbEmm/+RGU66Xr+uKNjrii69EACp+Datdf6D4G8HeDURqVaE7dvJcOKsGos2ORn1rHmF2HqFIU85xcNnQT+9k0hUYKVOXd6TvgtITssfaH8iLNbQh40ic1WdJ5D9jHXfiUo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=1QTCLdbO; 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="1QTCLdbO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7D9EF1F00A3A; Thu, 2 Jul 2026 16:28:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783009686; bh=Fv5nlmaETBhULDtwvbD6vnsLCwUdTk6gpC4azq5j6K8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=1QTCLdbOAigPF2OA0MUS6Mf5QUyWtziDtSCWw/8FzC8o8kAVcTEegSaNTVIUrdjPf f15pxjY8h0UlirEFBR1e90m2ZmaNI8MMeLmCAWbyjdgcQEZH59MO0hT4yBMgvcHmGm OlkXiB25MJ5j9lUwgl9xuRBAeCoeU4AR0SYMpfPg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable@kernel.org, Sven Eckelmann , Sasha Levin Subject: [PATCH 5.15 42/95] batman-adv: frag: avoid underflow of TTL Date: Thu, 2 Jul 2026 18:19:45 +0200 Message-ID: <20260702155110.091718111@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260702155109.196223802@linuxfoundation.org> References: <20260702155109.196223802@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: Sven Eckelmann commit 493d9d2528e1a09b090e4b37f0f553def7bd5ce9 upstream. Packets with a TTL are using it to limit the amount of time this packet can be forwarded. But for batadv_frag_packet, the TTL was always only reduced but it was never evaluated. It could even underflow without any effect. Check the TTL in batadv_frag_skb_fwd() before attempting to prepare it for forwarding. This keeps it in sync with the not fragmented unicast packet. Cc: stable@kernel.org Fixes: 610bfc6bc99b ("batman-adv: Receive fragmented packets and merge") Signed-off-by: Sven Eckelmann Signed-off-by: Sasha Levin --- net/batman-adv/fragmentation.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c index fbf030c57ac04d..0138b0953e10b5 100644 --- a/net/batman-adv/fragmentation.c +++ b/net/batman-adv/fragmentation.c @@ -420,6 +420,13 @@ bool batadv_frag_skb_fwd(struct sk_buff *skb, */ total_size = ntohs(packet->total_size); if (total_size > neigh_node->if_incoming->net_dev->mtu) { + if (packet->ttl < 2) { + kfree_skb(skb); + *rx_result = NET_RX_DROP; + ret = true; + goto out; + } + if (skb_cow(skb, ETH_HLEN) < 0) { kfree_skb(skb); *rx_result = NET_RX_DROP; -- 2.53.0