On Tue, May 26, 2026 at 08:37:26PM +0200, Doruk Tan Ozturk wrote: > 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) > > Found by 0sec (https://0sec.ai) using automated source analysis. > > Fixes: 4c14a2fb5d14 ("mac802154: add llsec decryption method") > Fixes: 03556e4d0dbb ("mac802154: add llsec encryption method") > Cc: [email protected] > Reported-by: Doruk Tan Ozturk <[email protected]> > Closes: > https://lore.kernel.org/linux-wpan/[email protected]/ > Reviewed-by: Alexander Lobakin <[email protected]> > Signed-off-by: Doruk Tan Ozturk <[email protected]> > --- > v2: > - mark as net fix per Olek's review > - add Closes tag > - add Reviewed-by
FTR: An AI generated review of this patch is available on sashiko.dev. I believe that review can be treated in the context of possible follow-up and should not effect the progress of this patch.
