From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DD0391F2B88; Tue, 25 Aug 2026 13:48:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787665716; cv=none; b=p1H4JlBKoiTxp9EDQEX2XtOENTTYqUERYjY7y33PwDQBVuNnPxFE0i2lFU2YcO0G6ODWOye3rvrw9htYYJApGAiGFVuLmO9lf/JaBqvvcjpH/94e2t1wzw/yBrkJzNjL57nn3XVaEzkKVqOYvBeGblxh86ymgwHgdAoJTtxDjKI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787665716; c=relaxed/simple; bh=SDNw+DRpp6ULzUN6CSH2u+bB7BTk3Cz0U1mwKZab4bE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BqrrSJ1SmvIOpPWNJxLkP82gZx3o7POOmkMX5cpmbpB04DR9/I+QWtD0vxC8JSZDik4w7diuheoU51b1dImiQ0aZy6dR+WSuci382NH4J+8jqiRw97je+yEQco38BGkYAgYMsnMF4lmiz1Vl+izZUU9QeQQILqrSet+MzVQ+gx0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=F1I4pq0R; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="F1I4pq0R" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 412481F000E9; Tue, 25 Aug 2026 13:48:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787665714; bh=VAwd3f9vPcV2p6qTsOQUJtjB+CwKqzoa7MrJqAPnM9w=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=F1I4pq0RoEXiguR1dSbocI8JpJJbSZDSLoqHqFUpo5cXYnqQ+4jcB56TDBf3xkpTb eAu4nzHd3hzWgwKbQpv3uBmxgmYkHUgz+Or7EuNAfrhYVptdD8Jvh5VUINwtBVWqYV 2pcyop0wsTFf+c5h7M1zlrqhlIw8w66TFMRAxtz8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Doruk Tan Ozturk , Simon Horman , David Heidelberg Subject: [PATCH 6.6 41/87] nfc: llcp: bound the connect_sn TLV walk to the skb Date: Tue, 25 Aug 2026 15:26:04 +0200 Message-ID: <20260825132543.460897895@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260825132541.813800447@linuxfoundation.org> References: <20260825132541.813800447@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Doruk Tan Ozturk commit 55c68ac93e7dacc0f5f608b9c39dd4ff48cf28e8 upstream. Commit 27256cdb290e ("nfc: llcp: bound SNL TLV parsing to the skb and add length checks") fixed the unbounded TLV walk in nfc_llcp_recv_snl(), and commit d8bd2dedbde5 ("nfc: llcp: fix OOB read and u8 offset wrap in TLV parsers") subsequently bounded nfc_llcp_parse_gb_tlv() and nfc_llcp_parse_connection_tlv(). One sibling parser sharing the same pattern remains unbounded: nfc_llcp_connect_sn(). nfc_llcp_connect_sn() walks a TLV list, reading a two-byte header (type, length) followed by length bytes of value, without checking that the two header bytes or the declared length stay within the buffer. It returns a pointer to a service name of up to 255 bytes that may point past the end of the skb; it is subsequently consumed by memcmp() in nfc_llcp_sock_from_sn(). In addition tlv_array_len was computed as "skb->len - LLCP_HEADER_SIZE" in size_t, so a CONNECT/CC frame shorter than the LLCP header underflows to a huge length and the walk runs far past the buffer. nfc_llcp_connect_sn() is reachable from nfc_llcp_recv_connect() and nfc_llcp_recv_cc(), i.e. from received CONNECT and CC PDUs. A nearby NFC device can reach this without authentication; LLCP link activation happens automatically after NFC-DEP, and the nfc_llcp_rx_skb() dispatcher applies no minimum-length guard. Walk the TLV list by pointer, bounded by skb_tail_pointer(skb), and validate each declared length before use, matching the approach already used for nfc_llcp_recv_snl(). Starting the walk at &skb->data[LLCP_HEADER_SIZE] against the tail pointer also removes the size_t underflow for short frames. Found by 0sec automated security-research tooling (https://0sec.ai). Fixes: d646960f7986 ("NFC: Initial LLCP support") Cc: stable@vger.kernel.org Assisted-by: 0sec:claude-opus-4-8 Signed-off-by: Doruk Tan Ozturk Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260709131229.44477-1-doruk@0sec.ai Signed-off-by: David Heidelberg Signed-off-by: Greg Kroah-Hartman --- net/nfc/llcp_core.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) --- a/net/nfc/llcp_core.c +++ b/net/nfc/llcp_core.c @@ -847,13 +847,16 @@ static struct nfc_llcp_sock *nfc_llcp_so static const u8 *nfc_llcp_connect_sn(const struct sk_buff *skb, size_t *sn_len) { u8 type, length; - const u8 *tlv = &skb->data[2]; - size_t tlv_array_len = skb->len - LLCP_HEADER_SIZE, offset = 0; + const u8 *tlv = &skb->data[LLCP_HEADER_SIZE]; + const u8 *tlv_end = skb_tail_pointer(skb); - while (offset < tlv_array_len) { + while (tlv + 2 < tlv_end) { type = tlv[0]; length = tlv[1]; + if (tlv + 2 + length > tlv_end) + break; + pr_debug("type 0x%x length %d\n", type, length); if (type == LLCP_TLV_SN) { @@ -861,7 +864,6 @@ static const u8 *nfc_llcp_connect_sn(con return &tlv[2]; } - offset += length + 2; tlv += length + 2; }