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 E438251C337; Wed, 30 Sep 2026 18:39:08 +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=1790793550; cv=none; b=J8wlvl1xajaQDPJJDOATvw1j/AtwNTn7aGN1LaH49f86MtJtNQiG3BeUJZotEULS5shWh1WvLSpLcZ69oqeJNxHHay3S9cQLs7amIakGMdAORXrOlP1r68EsuhBYQP/0Ne2ULaY/12j0jfUeHTT9YQKLMMgMSY3NwBCyLqaPQF0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790793550; c=relaxed/simple; bh=EPY1AuOLKCg7+GYuHqqv+5gBRsmBJhokH7bEUAXD2ZM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=asDY+8XCUYiD8MPzR2FHzKIVHS2aE1ajotIB89uI1efEdF6ckr2jn+AMgK0EHLT2RwHESILMDWqv16yXvvT2JWahruzV4q6BsPf0n/VYVJXxoWPVQzMhHLkUDno1q5dazU9o0eZ/fbZLfGW7cTyERMNYAZ+FLY2dVs9eMv6Djno= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=gDPb/VUj; 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="gDPb/VUj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4AEDE1F000FF; Wed, 30 Sep 2026 18:39:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790793548; bh=ftKxYfqejcY/M3XknuF7pZVr6DyLUJPoAuLcGeb/Acs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=gDPb/VUjkX/frJOce/q5CjBaRq6dxl+0lfBa+CLiR10cder7vdibMlN3Ofk7RPakg l0nQqoBcIqHgBiBGpwb4L+X28zOus8Ko91rjPiNGz25vbhWev6jffJm1it9VHG5mG5 hPxO59CNG3eGUBS9Ap+DxIXa+bn6L1/2BQ5rvU1Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Aamir Ahmed , Simon Horman , David Heidelberg Subject: [PATCH 6.18 294/395] nfc: llcp: drop truncated I/RR/RNR PDUs in nfc_llcp_recv_hdlc() Date: Wed, 30 Sep 2026 17:29:16 +0200 Message-ID: <20260930152347.035724101@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152340.591469096@linuxfoundation.org> References: <20260930152340.591469096@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Aamir Ahmed commit 273f9d667cde649f8de9d72b1303cc2f4b658c50 upstream. nfc_llcp_recv_hdlc() reads the sequence byte skb->data[2], via nfc_llcp_ns()/nfc_llcp_nr(), before any length check. The receive path only guarantees the two-byte LLCP header -- __nfc_llcp_recv() checks it with pskb_may_pull() and nfc_llcp_recv_agf() admits two-byte inner PDUs -- so a two-byte I, RR or RNR PDU reads one byte of uninitialised skb tailroom. The byte becomes N(R)/N(S); a peer can already set those with a well-formed PDU, so this is acting on uninitialised memory, not new peer control. Guard the read with pskb_may_pull(), as commit 95674f506c63 ("nfc: llcp: reject PDUs shorter than the LLCP header") did for the two-byte header, so the sequence byte is present and linear before it is read. RR and RNR PDUs are LLCP_HEADER_SIZE + LLCP_SEQUENCE_SIZE bytes and an I PDU is longer, so no valid frame is rejected; a truncated PDU is malformed, so return without a DM reply. Fixes: d646960f7986 ("NFC: Initial LLCP support") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Aamir Ahmed Reviewed-by: Simon Horman Link: https://patch.msgid.link/AS8P251MB0001789BBF04B72745C7D96BC8BA2@AS8P251MB0001.EURP251.PROD.OUTLOOK.COM Signed-off-by: David Heidelberg Signed-off-by: Greg Kroah-Hartman --- net/nfc/llcp_core.c | 3 +++ 1 file changed, 3 insertions(+) --- a/net/nfc/llcp_core.c +++ b/net/nfc/llcp_core.c @@ -1101,6 +1101,9 @@ static void nfc_llcp_recv_hdlc(struct nf struct sock *sk; u8 dsap, ssap, ptype, ns, nr; + if (!pskb_may_pull(skb, LLCP_HEADER_SIZE + LLCP_SEQUENCE_SIZE)) + return; + ptype = nfc_llcp_ptype(skb); dsap = nfc_llcp_dsap(skb); ssap = nfc_llcp_ssap(skb);