From: Doruk Tan Ozturk Date: Thu, 16 Jul 2026 19:34:23 +0000 (+0200) Subject: mac802154: llsec: reject frames shorter than the authentication tag X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=fd3a3f28ed60c6af4b2a39933b151d6b27842c3b;p=thirdparty%2Fkernel%2Flinux.git mac802154: llsec: reject frames shorter than the authentication tag llsec_do_decrypt_auth() computes the associated-data length for the AEAD request as assoclen += datalen - authlen; where datalen is the number of bytes after the MAC header and authlen (4, 8 or 16) is the length of the authentication tag. Nothing verifies that the frame actually carries at least authlen payload bytes. A secured frame whose payload is shorter than the tag makes datalen - authlen negative; assoclen is then passed to aead_request_set_ad() as an unsigned value close to 4 GiB, so crypto_aead_decrypt() walks far off the end of the scatterlist that only spans the real frame. The frame is fully attacker-controlled and reaches this path from any IEEE 802.15.4 peer in radio range. Reject frames whose payload is shorter than the authentication tag before the subtraction. Dynamically reproduced on a KASAN kernel as a general-protection-fault in the AEAD scatterwalk, and the fix confirmed. Fixes: 4c14a2fb5d14 ("mac802154: add llsec decryption method") Cc: stable@vger.kernel.org Reviewed-by: Simon Horman Signed-off-by: Doruk Tan Ozturk Link: https://patch.msgid.link/20260716193423.32498-1-doruk@0sec.ai Signed-off-by: Jakub Kicinski --- diff --git a/net/mac802154/llsec.c b/net/mac802154/llsec.c index 5e7cc11fab3a..85452ef9a58c 100644 --- a/net/mac802154/llsec.c +++ b/net/mac802154/llsec.c @@ -891,6 +891,11 @@ llsec_do_decrypt_auth(struct sk_buff *skb, const struct mac802154_llsec *sec, data = skb_mac_header(skb) + skb->mac_len; datalen = skb_tail_pointer(skb) - data; + if (datalen < authlen) { + kfree_sensitive(req); + return -EBADMSG; + } + sg_init_one(&sg, skb_mac_header(skb), assoclen + datalen); if (!(hdr->sec.level & IEEE802154_SCF_SECLEVEL_ENC)) {