From patchwork Tue Dec 12 18:49:18 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Siddh Raman Pant X-Patchwork-Id: 13489777 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=siddh.me header.i=code@siddh.me header.b="qJDjqT1P" Received: from sender-of-o51.zoho.in (sender-of-o51.zoho.in [103.117.158.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6EB41D0; Tue, 12 Dec 2023 10:49:56 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1702406967; cv=none; d=zohomail.in; s=zohoarc; b=OEDbM/7Nh+ThCBsFEQCeUubWdsTOEL0mGX/WzouBF5FpVS4sOTYuO2tOUkbBrOTds2pYNTJCQ5CIYGSn3R1uZnZnOq1swBXt782sMcecgey0PZNjaEycKghALTTK02XTlzFkb2hOym5ITH/n0alRrAyKnVEd3ru7WCElqbY2qW8= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.in; s=zohoarc; t=1702406967; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:MIME-Version:Message-ID:Subject:Subject:To:To:Message-Id:Reply-To; bh=Y9BKQtIfmMm0sVY++cu3R+sS5q4tdRr2o2bcRqoIeps=; b=CJqBDTw3OYrKBVuWr/2Kro6k7cevoqsJY2QRpxKn4AdYKipiHrgAlh9FnsGSViqMgzkTiJwqrrwOFUgT+z5w3FCa2R7dwDqRalqhhaHbgCEbxpEwosAkj1ReDaLHBvANVUCVxCrwZ1NYH1V8tFasJ5BjPOBac02YSMjAb3YDjMw= ARC-Authentication-Results: i=1; mx.zohomail.in; dkim=pass header.i=siddh.me; spf=pass smtp.mailfrom=code@siddh.me; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1702406967; s=zmail; d=siddh.me; i=code@siddh.me; h=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To; bh=Y9BKQtIfmMm0sVY++cu3R+sS5q4tdRr2o2bcRqoIeps=; b=qJDjqT1P2Rcgd2vYjnvrmn/yBZknNWDIc7p+MFgb5DfZoxdjMuvY+bsslJBPKNpm H69CGMzXQtO6Jxt/FTHtdGJXgkTn75sjhhTxWVVPK0UhbSPhYzEfhxAU7ghlUXUFEC0 DNK6TC2esVHvQ7dEuHNEtuJFPr1ZgJf/CsyVpAj8= Received: from kampyooter.. (182.69.31.144 [182.69.31.144]) by mx.zoho.in with SMTPS id 1702406965316224.42754580873793; Wed, 13 Dec 2023 00:19:25 +0530 (IST) From: Siddh Raman Pant To: Krzysztof Kozlowski , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Suman Ghosh Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net-next v5 0/2] nfc: Fix UAF during datagram sending caused by missing refcounting Date: Wed, 13 Dec 2023 00:19:18 +0530 Message-ID: X-Mailer: git-send-email 2.42.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ZohoMailClient: External X-Patchwork-Delegate: kuba@kernel.org Changes in v5: - Move reason = LLCP_DM_REJ under the fail_put_sock label. - Checkpatch now warns about == NULL check for new_sk, so fix that, and also at other similar places in the same function. Changes in v4: - Fix put ordering and comments. - Separate freeing in recv() into end labels. - Remove obvious comment and add reasoning. - Picked up r-bs by Suman. Changes in v3: - Fix missing freeing statements. Changes in v2: - Add net-next in patch subject. - Removed unnecessary extra lock and hold nfc_dev ref when holding llcp_sock. - Remove last formatting patch. - Picked up r-b from Krzysztof for LLCP_BOUND patch. --- For connectionless transmission, llcp_sock_sendmsg() codepath will eventually call nfc_alloc_send_skb() which takes in an nfc_dev as an argument for calculating the total size for skb allocation. virtual_ncidev_close() codepath eventually releases socket by calling nfc_llcp_socket_release() (which sets the sk->sk_state to LLCP_CLOSED) and afterwards the nfc_dev will be eventually freed. When an ndev gets freed, llcp_sock_sendmsg() will result in an use-after-free as it (1) doesn't have any checks in place for avoiding the datagram sending. (2) calls nfc_llcp_send_ui_frame(), which also has a do-while loop which can race with freeing. This loop contains the call to nfc_alloc_send_skb() where we dereference the nfc_dev pointer. nfc_dev is being freed because we do not hold a reference to it when we hold a reference to llcp_local. Thus, virtual_ncidev_close() eventually calls nfc_release() due to refcount going to 0. Since state has to be LLCP_BOUND for datagram sending, we can bail out early in llcp_sock_sendmsg(). Please review and let me know if any errors are there, and hopefully this gets accepted. Thanks, Siddh Siddh Raman Pant (2): nfc: llcp_core: Hold a ref to llcp_local->dev when holding a ref to llcp_local nfc: Do not send datagram if socket state isn't LLCP_BOUND net/nfc/llcp_core.c | 72 +++++++++++++++++++++++++++++---------------- net/nfc/llcp_sock.c | 5 ++++ 2 files changed, 52 insertions(+), 25 deletions(-)