From: Stanislav Fort Date: Sun, 31 Aug 2025 14:56:23 +0000 (+0200) Subject: batman-adv: fix OOB read/write in network-coding decode X-Git-Tag: v6.17-rc5~21^2~33^2 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=d77b6ff0ce35a6d0b0b7b9581bc3f76d041d4087;p=users%2Fgriffoul%2Flinux.git batman-adv: fix OOB read/write in network-coding decode batadv_nc_skb_decode_packet() trusts coded_len and checks only against skb->len. XOR starts at sizeof(struct batadv_unicast_packet), reducing payload headroom, and the source skb length is not verified, allowing an out-of-bounds read and a small out-of-bounds write. Validate that coded_len fits within the payload area of both destination and source sk_buffs before XORing. Fixes: 2df5278b0267 ("batman-adv: network coding - receive coded packets and decode them") Cc: stable@vger.kernel.org Reported-by: Stanislav Fort Signed-off-by: Stanislav Fort Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich --- diff --git a/net/batman-adv/network-coding.c b/net/batman-adv/network-coding.c index 9f56308779cc..af97d077369f 100644 --- a/net/batman-adv/network-coding.c +++ b/net/batman-adv/network-coding.c @@ -1687,7 +1687,12 @@ batadv_nc_skb_decode_packet(struct batadv_priv *bat_priv, struct sk_buff *skb, coding_len = ntohs(coded_packet_tmp.coded_len); - if (coding_len > skb->len) + /* ensure dst buffer is large enough (payload only) */ + if (coding_len + h_size > skb->len) + return NULL; + + /* ensure src buffer is large enough (payload only) */ + if (coding_len + h_size > nc_packet->skb->len) return NULL; /* Here the magic is reversed: