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 913EA471431; Tue, 25 Aug 2026 13:35:01 +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=1787664902; cv=none; b=AjdhQNIhw/8Xw+gIY4EoKq9mb7F9z0fuU+0kv5q8kbc7RgPlM+x1KWcdiC2+so64Qy37v48TXfX5XjsaLNbLIZxGCLQRJ/wF9LIBkImPVjwjmPuTDs3chHszfFZ/yxsf9uogGj3dWNx8hcxxMmI72Yg+6E0Xa1sY+y+xBgS27wI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787664902; c=relaxed/simple; bh=xbW+i/+fgCpnrhplu1vy/E5vZltxtxLEQQg1pwtnJjw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=f9UMIICpG1xCIQ6sHibMC6Eh9IF8/o/VPtwvKvCcqnaV7wgMgKFU7biZobAw66D+bo2w9dGlQxOqrViUMj93FDRPz+5F/nmGPzP+adhogytvrMmZbqPUiXZphdLVN8/wQV/QxbvAwnst5uZN9sUFcWHUJmZQMXnJOQTWATynDTQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rLBoZpoH; 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="rLBoZpoH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E4C711F000E9; Tue, 25 Aug 2026 13:35:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787664901; bh=4SmOZ5GRDSijCROk8yum/TPWBQ3WnxXwVwUOr8xMaGY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=rLBoZpoH+swhWHRjmk/ts3BlUr40NijRzALvfVKoG6HI83ljGtnEanIQUg5e3QbhO I12yOiCZ2cfxYrbL0Gln3FiyJHAdso1qM2XYTCEFYecUnDaQwwyytOhmPOoj1UwB3q MPtguZrc29KMnkgiAiQR+ks1yswlmjv/GxmRfH/A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Laight , Doruk Tan Ozturk , Vadim Fedorenko , David Heidelberg Subject: [PATCH 7.1 042/101] nfc: llcp: reject PDUs shorter than the LLCP header Date: Tue, 25 Aug 2026 15:25:20 +0200 Message-ID: <20260825132543.664995027@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260825132541.986300899@linuxfoundation.org> References: <20260825132541.986300899@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 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Doruk Tan Ozturk commit 95674f506c6376d6722a23144c9acd26609771ed upstream. Every LLCP PDU begins with a two-byte header (DSAP/SSAP + PTYPE), but the receive path never checked that a frame is at least LLCP_HEADER_SIZE bytes before parsing it. nfc_llcp_rx_skb() reads the header via nfc_llcp_ptype()/nfc_llcp_dsap()/ nfc_llcp_ssap(), which dereference pdu->data[0] and pdu->data[1], and a CONNECT or CC PDU then computes tlv_array_len = skb->len - LLCP_HEADER_SIZE; as a size_t and hands it to the TLV walk. When the frame is shorter than the header the subtraction wraps to a huge value and the walk runs far past the buffer, an out-of-bounds read. A nearby NFC device can reach this without authentication; LLCP link activation happens automatically after NFC-DEP. Guard the common receive choke point __nfc_llcp_recv(), shared by both the target (nfc_llcp_data_received()) and initiator (nfc_llcp_recv()) paths, so a short skb is dropped before the rx_work worker parses it. Use pskb_may_pull() rather than a skb->len test so the two header bytes are guaranteed to sit in the skb linear area even for a non-linear skb, matching how the sibling NCI and HCI receive paths validate their headers. Reproduced with a KFENCE out-of-bounds read via /dev/virtual_nci on linux-next. Found by 0sec automated security-research tooling (https://0sec.ai). Fixes: d646960f7986 ("NFC: Initial LLCP support") Cc: stable@vger.kernel.org Suggested-by: David Laight Signed-off-by: Doruk Tan Ozturk Reviewed-by: Vadim Fedorenko Link: https://patch.msgid.link/20260714164631.75068-1-doruk@0sec.ai Signed-off-by: David Heidelberg Signed-off-by: Greg Kroah-Hartman --- net/nfc/llcp_core.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/net/nfc/llcp_core.c +++ b/net/nfc/llcp_core.c @@ -1554,6 +1554,11 @@ static void nfc_llcp_rx_work(struct work static void __nfc_llcp_recv(struct nfc_llcp_local *local, struct sk_buff *skb) { + if (!pskb_may_pull(skb, LLCP_HEADER_SIZE)) { + kfree_skb(skb); + return; + } + local->rx_pending = skb; timer_delete(&local->link_timer); schedule_work(&local->rx_work);