From patchwork Tue Dec 19 17:49:42 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: 13498778 Received: from sender-of-o51.zoho.in (sender-of-o51.zoho.in [103.117.158.51]) (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 2E0C0374FB; Tue, 19 Dec 2023 17:50:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=siddh.me Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=siddh.me Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=siddh.me header.i=code@siddh.me header.b="itoo7OK8" ARC-Seal: i=1; a=rsa-sha256; t=1703008191; cv=none; d=zohomail.in; s=zohoarc; b=QOyVkYFTtehlwMgXA2ZYoTfaWgXSd7e0EpVAQQhTPu2E2XzKSFhFpo2B8n1L2SYtz8DpDRUOM6mziNNXuD1Zd9rcUcZpHJDu7OQJr8KmCLaBVsA6ujPxwMPW/Ybp2Y2dO4ZGx2ftS0UrtNE2AXh7NvO93tWZt1VtKjLgIWGS9W8= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.in; s=zohoarc; t=1703008191; h=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:MIME-Version:Message-ID:Subject:Subject:To:To:Message-Id:Reply-To; bh=AF+NCNsa1eutOHcZrZ045IS0+FsNjuyaPy8+4b1PvQU=; b=QhBkOfPbqj542fHj0H2AINnX85mdPtraoEot6EalN/QvrFVuwbXR0pMyRaknCycWWhGSPxEew8wUSuEtkEnyu/2gGni6+R1MdAdiAxHb7COWxySp0NMKoTOs4/z5zte2Dox87C+0hluq6WtwUKn68O/n6EZH5GNmt811bkP4GEU= 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=1703008191; 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=AF+NCNsa1eutOHcZrZ045IS0+FsNjuyaPy8+4b1PvQU=; b=itoo7OK8xmy9lIdJMp9qpWvoSb/J3qowZhsccfulphFDGZG9QM/sBNBSCUsozWjz XSquQRvK9wKTCVq4gkndIEJ4z05OO4phxoxBeLOmyrWcyc+ISlO5fB2fAfCsGfVTPWb NekMrLpM1GeclQKgKGXkcAVOOWzd/CbEiwpADgtI= Received: from kampyooter.. (122.170.167.40 [122.170.167.40]) by mx.zoho.in with SMTPS id 1703008190516661.7229040711136; Tue, 19 Dec 2023 23:19:50 +0530 (IST) From: Siddh Raman Pant To: Krzysztof Kozlowski , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net-next v7 0/2] nfc: Fix UAF during datagram sending caused by missing refcounting Date: Tue, 19 Dec 2023 23:19:42 +0530 Message-ID: X-Mailer: git-send-email 2.43.0 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 v7: - Stupidly reverted ordering in recv() too, fix that. - Remove redundant call to nfc_llcp_sock_free(). Changes in v6: - Revert label introduction from v4, and thus also v5 entirely. 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 | 39 ++++++++++++++++++++++++++++++++++++--- net/nfc/llcp_sock.c | 5 +++++ 2 files changed, 41 insertions(+), 3 deletions(-)