From: Sven Eckelmann <[email protected]> The fields of an aggregated OGM(v2) are accessed assuming (at least) 2-byte alignment, so a following OGM must start at an even offset. As the header length is even, an odd tvlv_len would misalign it and trigger unaligned accesses on strict-alignment architectures.
Such a misaligned TVLV/OGM/OGMv2 is not created by a normal participant in the mesh. Therefore, reject such malformed packets. Cc: [email protected] Fixes: ef26157747d4 ("batman-adv: tvlv - basic infrastructure") Signed-off-by: Sven Eckelmann <[email protected]> Signed-off-by: Simon Wunderlich <[email protected]> --- net/batman-adv/bat_iv_ogm.c | 11 ++++++++++- net/batman-adv/bat_v_ogm.c | 11 ++++++++++- net/batman-adv/routing.c | 6 ++++++ net/batman-adv/tvlv.c | 6 ++++++ 4 files changed, 32 insertions(+), 2 deletions(-) diff --git a/net/batman-adv/bat_iv_ogm.c b/net/batman-adv/bat_iv_ogm.c index 7588e64e7ba6f..bb2f012b454ea 100644 --- a/net/batman-adv/bat_iv_ogm.c +++ b/net/batman-adv/bat_iv_ogm.c @@ -316,14 +316,23 @@ batadv_iv_ogm_aggr_packet(int buff_pos, int packet_len, const struct batadv_ogm_packet *ogm_packet) { int next_buff_pos = 0; + u16 tvlv_len; /* check if there is enough space for the header */ next_buff_pos += buff_pos + sizeof(*ogm_packet); if (next_buff_pos > packet_len) return false; + tvlv_len = ntohs(ogm_packet->tvlv_len); + + /* the fields of an aggregated OGM are accessed assuming (at least) + * 2-byte alignment, so a following OGM must start at an even offset. + */ + if (tvlv_len & 1) + return false; + /* check if there is enough space for the optional TVLV */ - next_buff_pos += ntohs(ogm_packet->tvlv_len); + next_buff_pos += tvlv_len; return next_buff_pos <= packet_len; } diff --git a/net/batman-adv/bat_v_ogm.c b/net/batman-adv/bat_v_ogm.c index 95efd8a43c79d..037921aad35d5 100644 --- a/net/batman-adv/bat_v_ogm.c +++ b/net/batman-adv/bat_v_ogm.c @@ -849,14 +849,23 @@ batadv_v_ogm_aggr_packet(int buff_pos, int packet_len, const struct batadv_ogm2_packet *ogm2_packet) { int next_buff_pos = 0; + u16 tvlv_len; /* check if there is enough space for the header */ next_buff_pos += buff_pos + sizeof(*ogm2_packet); if (next_buff_pos > packet_len) return false; + tvlv_len = ntohs(ogm2_packet->tvlv_len); + + /* the fields of an aggregated OGMv2 are accessed assuming (at least) + * 2-byte alignment, so a following OGMv2 must start at an even offset. + */ + if (tvlv_len & 1) + return false; + /* check if there is enough space for the optional TVLV */ - next_buff_pos += ntohs(ogm2_packet->tvlv_len); + next_buff_pos += tvlv_len; return next_buff_pos <= packet_len; } diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c index 9db57fd36e7d4..c05fcc9241add 100644 --- a/net/batman-adv/routing.c +++ b/net/batman-adv/routing.c @@ -1366,6 +1366,12 @@ int batadv_recv_mcast_packet(struct sk_buff *skb, if (tvlv_buff_len > skb->len - hdr_size) goto free_skb; + /* the fields of an multicast payload are accessed assuming (at least) + * 2-byte alignment, so a following packet must start at an even offset. + */ + if (tvlv_buff_len & 1) + goto free_skb; + ret = batadv_tvlv_containers_process(bat_priv, BATADV_MCAST, NULL, skb, tvlv_buff, tvlv_buff_len); if (ret >= 0) { diff --git a/net/batman-adv/tvlv.c b/net/batman-adv/tvlv.c index 403c854568704..a957555d8958d 100644 --- a/net/batman-adv/tvlv.c +++ b/net/batman-adv/tvlv.c @@ -477,6 +477,12 @@ int batadv_tvlv_containers_process(struct batadv_priv *bat_priv, if (tvlv_value_cont_len > tvlv_value_len) break; + /* the next tvlv header is accessed assuming (at least) 2-byte + * alignment, so it must start at an even offset. + */ + if (tvlv_value_cont_len & 1) + break; + tvlv_handler = batadv_tvlv_handler_get(bat_priv, tvlv_hdr->type, tvlv_hdr->version); -- 2.47.3
