61 lines
2.4 KiB
Diff
61 lines
2.4 KiB
Diff
From: Sven Eckelmann <sven@narfation.org>
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Date: Fri, 23 Aug 2019 14:34:28 +0200
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Subject: batman-adv: Only read OGM2 tvlv_len after buffer len check
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Multiple batadv_ogm2_packet can be stored in an skbuff. The functions
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batadv_v_ogm_send_to_if() uses batadv_v_ogm_aggr_packet() to check if there
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is another additional batadv_ogm2_packet in the skb or not before they
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continue processing the packet.
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The length for such an OGM2 is BATADV_OGM2_HLEN +
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batadv_ogm2_packet->tvlv_len. The check must first check that at least
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BATADV_OGM2_HLEN bytes are available before it accesses tvlv_len (which is
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part of the header. Otherwise it might try read outside of the currently
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available skbuff to get the content of tvlv_len.
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Fixes: 667996ebeab4 ("batman-adv: OGMv2 - implement originators logic")
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Signed-off-by: Sven Eckelmann <sven@narfation.org>
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Origin: upstream, https://git.open-mesh.org/batman-adv.git/commit/18f77da3761c5550f42a2d131f0fe5cac62e022d
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--- a/net/batman-adv/bat_v_ogm.c
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+++ b/net/batman-adv/bat_v_ogm.c
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@@ -631,17 +631,23 @@ batadv_v_ogm_process_per_outif(struct ba
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* batadv_v_ogm_aggr_packet() - checks if there is another OGM aggregated
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* @buff_pos: current position in the skb
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* @packet_len: total length of the skb
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- * @tvlv_len: tvlv length of the previously considered OGM
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+ * @ogm2_packet: potential OGM2 in buffer
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*
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* Return: true if there is enough space for another OGM, false otherwise.
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*/
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-static bool batadv_v_ogm_aggr_packet(int buff_pos, int packet_len,
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- __be16 tvlv_len)
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+static bool
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+batadv_v_ogm_aggr_packet(int buff_pos, int packet_len,
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+ const struct batadv_ogm2_packet *ogm2_packet)
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{
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int next_buff_pos = 0;
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- next_buff_pos += buff_pos + BATADV_OGM2_HLEN;
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- next_buff_pos += ntohs(tvlv_len);
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+ /* check if there is enough space for the header */
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+ next_buff_pos += buff_pos + sizeof(*ogm2_packet);
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+ if (next_buff_pos > packet_len)
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+ return false;
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+
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+ /* check if there is enough space for the optional TVLV */
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+ next_buff_pos += ntohs(ogm2_packet->tvlv_len);
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return (next_buff_pos <= packet_len) &&
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(next_buff_pos <= BATADV_MAX_AGGREGATION_BYTES);
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@@ -818,7 +824,7 @@ int batadv_v_ogm_packet_recv(struct sk_b
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ogm_packet = (struct batadv_ogm2_packet *)skb->data;
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while (batadv_v_ogm_aggr_packet(ogm_offset, skb_headlen(skb),
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- ogm_packet->tvlv_len)) {
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+ ogm_packet)) {
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batadv_v_ogm_process(skb, ogm_offset, if_incoming);
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ogm_offset += BATADV_OGM2_HLEN;
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