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 E5CA847ECF6; Tue, 25 Aug 2026 13:31:36 +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=1787664698; cv=none; b=D15kJAdeHIVqqIsrk5hah2lGm3oZ1+nFZyBGqfyjIt5qh1TCQX30AMyIEBniqslX3ESj7nP11X4XoGcqZgAobW2gdauaMwdFwZ8we6n6UCnwl3eiC1s5MAJ4LVBoRxB1xJNfHPPbyBoDXT2QVDrPB3BXrLu75hogwovN+0qbw5w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787664698; c=relaxed/simple; bh=vP8KPu8ARSmoiwaC1VnksK/MEU9B700rvSlVEKcdufY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OeC+EARoA+3Zlj79fxqJcrm/wCXYMUakdcziPNm75FCf49A6INWdEjkVwGIMSpQYVPx8iMoQCeNSG2gCDu17BUe0vuXumDyScU516dpjHf8XvCJHJ3ad9p8LmpMKf24e+V2ubJ4+Tb/1J1tpXgGgfrfSoxgWhU1ZIjyTJnVYZSE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=DC73uQcc; 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="DC73uQcc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE83F1F000E9; Tue, 25 Aug 2026 13:31:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1787664696; bh=idg0o/H38/505dOEYKWJujGrbNg46sODPdDZQqJuUFs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DC73uQcchrR3m5RPcpvCtpzl4Ut3MY5eBL5U0V1mQ2+nGFmF1blYR+ZmAFXunL8QA +fZu2GjXb8E96t5Mkbqy71wDjFAsrrJ1rcb1fCO85hkQvSrE8xijp2RcF0OdIHhii7 KayAonJsrfv0LFTDTZE1SzqYrD9FsGhmIc6d1ogg= 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 7.2 39/82] nfc: llcp: reject PDUs shorter than the LLCP header Date: Tue, 25 Aug 2026 15:25:26 +0200 Message-ID: <20260825132543.039085817@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260825132541.560541185@linuxfoundation.org> References: <20260825132541.560541185@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 7.2-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);