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 8DE373D9547; Tue, 25 Aug 2026 13:56:31 +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=1787666192; cv=none; b=h4Gm4bJSMb6vpzy4A+CZd6Y51WQ8Om8xlOVlgsFsefHpbFC3+NQbOe+5q5KbhInFrclIHBhYqG1CMjnWO/tG686bUGFMG9omJegOcHxA9vPBHQekbbKwDOZI/IENfxHqNj5ZV2KXEu/NKD8RttryaUwcP25ZVfYhldHqWZyKeJ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787666192; c=relaxed/simple; bh=JLGs+XxyOmujtcA11Ipgq0emsVGOsavZCHE/QCoGK3U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dW+qtCEc/ThUAwkWWxnnfvr6fgBehyCcsiS8YWGDfutKlCPw+5gm9Zt+U5uCacm0g79hXCXtuE5zH2nSx/O/bgdo+fbCxqIgmZZPtKy/+MuiGlAMQDGz+5GRITPtbzIfi1+ElVheKeuLCW+b9JYu0Sal3a5cj/+wE59mkiPtsp0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=v9STSUol; 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="v9STSUol" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DF6CD1F000E9; Tue, 25 Aug 2026 13:56:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787666191; bh=J8Z0TdKU39Ez+wLngs+dGM71veiEOQvmKX8z3Z5MPqg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=v9STSUolJ8v12YVIqIhQE3W2nCFwDaoo5Bvt+qgXo10dUcqYSJSlVoN0weacudnQz 6kdQ3EhSGuS4wZMrU0/89LtgDv/AO3PvR4is4En1OXVeGrYusupmlSNHzqkJudJaCW py5DMExlSZoOl/8Z5+qiEEPAMENpwF/7I08YH7UM= 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 5.15 34/76] nfc: llcp: reject PDUs shorter than the LLCP header Date: Tue, 25 Aug 2026 15:26:27 +0200 Message-ID: <20260825132542.895306331@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260825132541.568214149@linuxfoundation.org> References: <20260825132541.568214149@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 5.15-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 @@ -1561,6 +1561,11 @@ 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; del_timer(&local->link_timer); schedule_work(&local->rx_work);