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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , b.a.t.m.a.n@lists.open-mesh.org (moderated list:BATMAN ADVANCED), linux-kernel@vger.kernel.org (open list), disclosure@aisle.com, stable@vger.kernel.org Subject: [PATCH net v2] batman-adv: fix OOB read/write in network-coding decode Date: Sun, 31 Aug 2025 16:56:23 +0200 Message-Id: <20250831145623.63778-1-disclosure@aisle.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 an= d decode them") Cc: stable@vger.kernel.org Reported-by: Stanislav Fort Signed-off-by: Stanislav Fort --- 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-codin= g.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, =20 coding_len =3D ntohs(coded_packet_tmp.coded_len); =20 - 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; =20 /* Here the magic is reversed: --=20 2.39.3 (Apple Git-146)