llsec_do_encrypt_unauth(), llsec_do_encrypt_auth(), llsec_do_decrypt_unauth(), and llsec_do_decrypt_auth() all perform in-place cryptographic transformations on skb data. They build a scatterlist with sg_init_one() pointing into the skb's linear data area and then pass the same scatterlist as both src and dst to the crypto API (e.g. crypto_skcipher_encrypt/decrypt, crypto_aead_encrypt/decrypt). On the RX path, __ieee802154_rx_handle_packet() clones the received skb before handing it to each subscriber via ieee802154_subif_frame(). The cloned skb shares the same underlying data buffer via reference counting. When llsec_do_decrypt() subsequently modifies this shared buffer in place, it corrupts data that other clones -- potentially belonging to other sockets or subsystems -- still reference. On the TX path, similar data sharing can occur when an skb's head has been cloned (skb_cloned() returns true). The fix is to call skb_cow_data() before performing any in-place crypto operation. skb_cow_data() ensures that the skb's data area is not shared: if the skb head is cloned or the data spans multiple fragments, it copies the data into a private buffer that can be safely modified in place. This is the same pattern used by: - ESP (net/ipv4/esp4.c, net/ipv6/esp6.c) - MACsec (drivers/net/macsec.c) - WireGuard (drivers/net/wireguard/receive.c) - TIPC (net/tipc/crypto.c) Without this guard, in-place crypto on shared skb data leads to: - Silent data corruption of other skb clones - Use-after-free when the crypto API scatterwalk writes through a page that has already been freed by another clone's kfree_skb() - Kernel crashes under concurrent 802.15.4 traffic with security enabled (KASAN/KMSAN reports slab-use-after-free) This vulnerability was identified using 0sec.ai, an open-source automated security auditing platform (https://github.com/0sec-labs). Fixes: 4c14a2fb5d14 ("mac802154: add llsec decryption method") Fixes: 03556e4d0dbb ("mac802154: add llsec encryption method") Cc: stable@vger.kernel.org Reported-by: Doruk Tan Ozturk Signed-off-by: Doruk Tan Ozturk --- net/mac802154/llsec.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/net/mac802154/llsec.c b/net/mac802154/llsec.c index e8512578398e..b6a4a8c93d72 100644 --- a/net/mac802154/llsec.c +++ b/net/mac802154/llsec.c @@ -710,6 +710,7 @@ int mac802154_llsec_encrypt(struct mac802154_llsec *sec, struct sk_buff *skb) { struct ieee802154_hdr hdr; int rc, authlen, hlen; + struct sk_buff *trailer; struct mac802154_llsec_key *key; u32 frame_ctr; @@ -769,6 +770,12 @@ int mac802154_llsec_encrypt(struct mac802154_llsec *sec, struct sk_buff *skb) skb->mac_len = ieee802154_hdr_push(skb, &hdr); skb_reset_mac_header(skb); + rc = skb_cow_data(skb, 0, &trailer); + if (rc < 0) { + llsec_key_put(key); + return rc; + } + rc = llsec_do_encrypt(skb, sec, &hdr, key); llsec_key_put(key); @@ -908,6 +915,13 @@ llsec_do_decrypt(struct sk_buff *skb, const struct mac802154_llsec *sec, const struct ieee802154_hdr *hdr, struct mac802154_llsec_key *key, __le64 dev_addr) { + struct sk_buff *trailer; + int err; + + err = skb_cow_data(skb, 0, &trailer); + if (err < 0) + return err; + if (hdr->sec.level == IEEE802154_SCF_SECLEVEL_ENC) return llsec_do_decrypt_unauth(skb, sec, hdr, key, dev_addr); else -- 2.45.0