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 disclosure@aisle.com Signed-off-by: Stanislav Fort disclosure@aisle.com --- net/batman-adv/network-coding.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)

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: