From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 602B8C4332F for ; Wed, 13 Dec 2023 07:40:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378673AbjLMHkR (ORCPT ); Wed, 13 Dec 2023 02:40:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38812 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233024AbjLMHkO (ORCPT ); Wed, 13 Dec 2023 02:40:14 -0500 Received: from mail-wm1-x32b.google.com (mail-wm1-x32b.google.com [IPv6:2a00:1450:4864:20::32b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 312F39B for ; Tue, 12 Dec 2023 23:40:20 -0800 (PST) Received: by mail-wm1-x32b.google.com with SMTP id 5b1f17b1804b1-40c1e3ea2f2so65455515e9.2 for ; Tue, 12 Dec 2023 23:40:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1702453218; x=1703058018; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:autocrypt:from:references:cc :to:content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=ohbTv7N8IBgSQDfoA8zt810Sv8vFOgNDA66r3vbXTsA=; b=gBwfHdv6UwP/qMnO6ZJOhqFgZC6vTlKJPPH2AKwmlWeci0cg+uI+1qQd4bRrv6VdHX IpsL3QcALdxovXiH/Tt/1eqDzbGlbrk5A+5noGFsm+P8wtHWsRQX0FBiaqKHoB5JgqcM d8zRXZynriswl9GNc2at+KyAmtPm6WiMtyQlFSaq4h7oxspVXUj8oe8NFkKojP4Euzd+ B8Fjs3/4Pgfqahp0+d5vWvZ0aVGjda9E29I6KkvRkEHqe8RbPmhr3xWoRBTd+xDS0jys 2cAhyiZw60mfEDaz1A3Wm85SNziLog2rjOOirznrUzNxIYa4q/NgTEXrCn5oP2vXrY5L +L3Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702453218; x=1703058018; h=content-transfer-encoding:in-reply-to:autocrypt:from:references:cc :to:content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=ohbTv7N8IBgSQDfoA8zt810Sv8vFOgNDA66r3vbXTsA=; b=uVleWsI7zqdmTIxmHU04aVXzAEndi+PXHKOq9AK/Rg6w5Sb+SyV7wirzWypanVnX70 J/aFu6WsNFzd65U/fJhQ2EelCtJ0ZEcj5dIAqws0jQYsyYG4T9IrsrZ8rOwDB31E7s/+ 5itqU//aCvHh3XfRTypvbvIvjxyrlztGQnynUgdM0UEpeWzLFVLdtKdVkVLhHGSEtjuJ QKi+BcxWrBTtInfgndDMAg57AWBwZybk2HSSObwewO63MvlHy00q/NuiU24lj75IFUUh xvQ1zKIg5KkLMC+rUUGhuM/Uxc0R9fvygiI0DYeGJFbFChNfSawNImhKQ6E4LjcNGo7B VKdA== X-Gm-Message-State: AOJu0YwKfeBJzlyFfOqh+2RYmb16r3gZeOR+DEyzMJSd/9SQOCEipx33 6OiZxI6tDDbmssSN0thWkWJXpg== X-Google-Smtp-Source: AGHT+IF6s2cTa+Lk2GrNTmyRn0J97TvRbNsB4rmkb50ZEF24BoMWh/6sbS+i/n0xIyucUslys9ED3w== X-Received: by 2002:a05:600c:6020:b0:40c:1e00:cfcc with SMTP id az32-20020a05600c602000b0040c1e00cfccmr4187542wmb.97.1702453218575; Tue, 12 Dec 2023 23:40:18 -0800 (PST) Received: from [192.168.1.20] ([178.197.218.27]) by smtp.gmail.com with ESMTPSA id l12-20020a05600c4f0c00b0040b4b2a15ebsm19317297wmq.28.2023.12.12.23.40.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Dec 2023 23:40:18 -0800 (PST) Message-ID: <1813902b-6afc-4539-96b2-050df6fc75c1@linaro.org> Date: Wed, 13 Dec 2023 08:40:16 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v5 1/2] nfc: llcp_core: Hold a ref to llcp_local->dev when holding a ref to llcp_local Content-Language: en-US To: Siddh Raman Pant , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Suman Ghosh Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+bbe84a4010eeea00982d@syzkaller.appspotmail.com References: <6a26e3b65817bb31cb11c8dde5b1b420071d944e.1702404519.git.code@siddh.me> From: Krzysztof Kozlowski Autocrypt: addr=krzysztof.kozlowski@linaro.org; keydata= xsFNBFVDQq4BEAC6KeLOfFsAvFMBsrCrJ2bCalhPv5+KQF2PS2+iwZI8BpRZoV+Bd5kWvN79 cFgcqTTuNHjAvxtUG8pQgGTHAObYs6xeYJtjUH0ZX6ndJ33FJYf5V3yXqqjcZ30FgHzJCFUu JMp7PSyMPzpUXfU12yfcRYVEMQrmplNZssmYhiTeVicuOOypWugZKVLGNm0IweVCaZ/DJDIH gNbpvVwjcKYrx85m9cBVEBUGaQP6AT7qlVCkrf50v8bofSIyVa2xmubbAwwFA1oxoOusjPIE J3iadrwpFvsZjF5uHAKS+7wHLoW9hVzOnLbX6ajk5Hf8Pb1m+VH/E8bPBNNYKkfTtypTDUCj NYcd27tjnXfG+SDs/EXNUAIRefCyvaRG7oRYF3Ec+2RgQDRnmmjCjoQNbFrJvJkFHlPeHaeS BosGY+XWKydnmsfY7SSnjAzLUGAFhLd/XDVpb1Een2XucPpKvt9ORF+48gy12FA5GduRLhQU vK4tU7ojoem/G23PcowM1CwPurC8sAVsQb9KmwTGh7rVz3ks3w/zfGBy3+WmLg++C2Wct6nM Pd8/6CBVjEWqD06/RjI2AnjIq5fSEH/BIfXXfC68nMp9BZoy3So4ZsbOlBmtAPvMYX6U8VwD TNeBxJu5Ex0Izf1NV9CzC3nNaFUYOY8KfN01X5SExAoVTr09ewARAQABzTRLcnp5c3p0b2Yg S296bG93c2tpIDxrcnp5c3p0b2Yua296bG93c2tpQGxpbmFyby5vcmc+wsGUBBMBCgA+FiEE m9B+DgxR+NWWd7dUG5NDfTtBYpsFAmI+BxMCGwMFCRRfreEFCwkIBwIGFQoJCAsCBBYCAwEC HgECF4AACgkQG5NDfTtBYptgbhAAjAGunRoOTduBeC7V6GGOQMYIT5n3OuDSzG1oZyM4kyvO XeodvvYv49/ng473E8ZFhXfrre+c1olbr1A8pnz9vKVQs9JGVa6wwr/6ddH7/yvcaCQnHRPK mnXyP2BViBlyDWQ71UC3N12YCoHE2cVmfrn4JeyK/gHCvcW3hUW4i5rMd5M5WZAeiJj3rvYh v8WMKDJOtZFXxwaYGbvFJNDdvdTHc2x2fGaWwmXMJn2xs1ZyFAeHQvrp49mS6PBQZzcx0XL5 cU9ZjhzOZDn6Apv45/C/lUJvPc3lo/pr5cmlOvPq1AsP6/xRXsEFX/SdvdxJ8w9KtGaxdJuf rpzLQ8Ht+H0lY2On1duYhmro8WglOypHy+TusYrDEry2qDNlc/bApQKtd9uqyDZ+rx8bGxyY qBP6bvsQx5YACI4p8R0J43tSqWwJTP/R5oPRQW2O1Ye1DEcdeyzZfifrQz58aoZrVQq+innR aDwu8qDB5UgmMQ7cjDSeAQABdghq7pqrA4P8lkA7qTG+aw8Z21OoAyZdUNm8NWJoQy8m4nUP gmeeQPRc0vjp5JkYPgTqwf08cluqO6vQuYL2YmwVBIbO7cE7LNGkPDA3RYMu+zPY9UUi/ln5 dcKuEStFZ5eqVyqVoZ9eu3RTCGIXAHe1NcfcMT9HT0DPp3+ieTxFx6RjY3kYTGLOwU0EVUNc NAEQAM2StBhJERQvgPcbCzjokShn0cRA4q2SvCOvOXD+0KapXMRFE+/PZeDyfv4dEKuCqeh0 hihSHlaxTzg3TcqUu54w2xYskG8Fq5tg3gm4kh1Gvh1LijIXX99ABA8eHxOGmLPRIBkXHqJY oHtCvPc6sYKNM9xbp6I4yF56xVLmHGJ61KaWKf5KKWYgA9kfHufbja7qR0c6H79LIsiYqf92 H1HNq1WlQpu/fh4/XAAaV1axHFt/dY/2kU05tLMj8GjeQDz1fHas7augL4argt4e+jum3Nwt yupodQBxncKAUbzwKcDrPqUFmfRbJ7ARw8491xQHZDsP82JRj4cOJX32sBg8nO2N5OsFJOcd 5IE9v6qfllkZDAh1Rb1h6DFYq9dcdPAHl4zOj9EHq99/CpyccOh7SrtWDNFFknCmLpowhct9 5ZnlavBrDbOV0W47gO33WkXMFI4il4y1+Bv89979rVYn8aBohEgET41SpyQz7fMkcaZU+ok/ +HYjC/qfDxT7tjKXqBQEscVODaFicsUkjheOD4BfWEcVUqa+XdUEciwG/SgNyxBZepj41oVq FPSVE+Ni2tNrW/e16b8mgXNngHSnbsr6pAIXZH3qFW+4TKPMGZ2rZ6zITrMip+12jgw4mGjy 5y06JZvA02rZT2k9aa7i9dUUFggaanI09jNGbRA/ABEBAAHCwXwEGAEKACYCGwwWIQSb0H4O DFH41ZZ3t1Qbk0N9O0FimwUCYDzvagUJFF+UtgAKCRAbk0N9O0Fim9JzD/0auoGtUu4mgnna oEEpQEOjgT7l9TVuO3Qa/SeH+E0m55y5Fjpp6ZToc481za3xAcxK/BtIX5Wn1mQ6+szfrJQ6 59y2io437BeuWIRjQniSxHz1kgtFECiV30yHRgOoQlzUea7FgsnuWdstgfWi6LxstswEzxLZ Sj1EqpXYZE4uLjh6dW292sO+j4LEqPYr53hyV4I2LPmptPE9Rb9yCTAbSUlzgjiyyjuXhcwM qf3lzsm02y7Ooq+ERVKiJzlvLd9tSe4jRx6Z6LMXhB21fa5DGs/tHAcUF35hSJrvMJzPT/+u /oVmYDFZkbLlqs2XpWaVCo2jv8+iHxZZ9FL7F6AHFzqEFdqGnJQqmEApiRqH6b4jRBOgJ+cY qc+rJggwMQcJL9F+oDm3wX47nr6jIsEB5ZftdybIzpMZ5V9v45lUwmdnMrSzZVgC4jRGXzsU EViBQt2CopXtHtYfPAO5nAkIvKSNp3jmGxZw4aTc5xoAZBLo0OV+Ezo71pg3AYvq0a3/oGRG KQ06ztUMRrj8eVtpImjsWCd0bDWRaaR4vqhCHvAG9iWXZu4qh3ipie2Y0oSJygcZT7H3UZxq fyYKiqEmRuqsvv6dcbblD8ZLkz1EVZL6djImH5zc5x8qpVxlA0A0i23v5QvN00m6G9NFF0Le D2GYIS41Kv4Isx2dEFh+/Q== In-Reply-To: <6a26e3b65817bb31cb11c8dde5b1b420071d944e.1702404519.git.code@siddh.me> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/12/2023 19:49, Siddh Raman Pant wrote: > llcp_sock_sendmsg() calls nfc_llcp_send_ui_frame() which in turn calls > nfc_alloc_send_skb(), which accesses the nfc_dev from the llcp_sock for > getting the headroom and tailroom needed for skb allocation. > > Parallelly the nfc_dev can be freed, as the refcount is decreased via > nfc_free_device(), leading to a UAF reported by Syzkaller, which can > be summarized as follows: > > (1) llcp_sock_sendmsg() -> nfc_llcp_send_ui_frame() > -> nfc_alloc_send_skb() -> Dereference *nfc_dev > (2) virtual_ncidev_close() -> nci_free_device() -> nfc_free_device() > -> put_device() -> nfc_release() -> Free *nfc_dev > > When a reference to llcp_local is acquired, we do not acquire the same > for the nfc_dev. This leads to freeing even when the llcp_local is in > use, and this is the case with the UAF described above too. > > Thus, when we acquire a reference to llcp_local, we should acquire a > reference to nfc_dev, and release the references appropriately later. > > References for llcp_local is initialized in nfc_llcp_register_device() > (which is called by nfc_register_device()). Thus, we should acquire a > reference to nfc_dev there. > > nfc_unregister_device() calls nfc_llcp_unregister_device() which in > turn calls nfc_llcp_local_put(). Thus, the reference to nfc_dev is > appropriately released later. > > Reported-and-tested-by: syzbot+bbe84a4010eeea00982d@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=bbe84a4010eeea00982d > Fixes: c7aa12252f51 ("NFC: Take a reference on the LLCP local pointer when creating a socket") > Reviewed-by: Suman Ghosh > Signed-off-by: Siddh Raman Pant > --- > net/nfc/llcp_core.c | 72 +++++++++++++++++++++++++++++---------------- > 1 file changed, 47 insertions(+), 25 deletions(-) > > diff --git a/net/nfc/llcp_core.c b/net/nfc/llcp_core.c > index 1dac28136e6a..2f77200a3720 100644 > --- a/net/nfc/llcp_core.c > +++ b/net/nfc/llcp_core.c > @@ -145,6 +145,13 @@ static void nfc_llcp_socket_release(struct nfc_llcp_local *local, bool device, > > static struct nfc_llcp_local *nfc_llcp_local_get(struct nfc_llcp_local *local) > { > + /* Since using nfc_llcp_local may result in usage of nfc_dev, whenever > + * we hold a reference to local, we also need to hold a reference to > + * the device to avoid UAF. > + */ > + if (!nfc_get_device(local->dev->idx)) > + return NULL; > + > kref_get(&local->ref); > > return local; > @@ -177,10 +184,18 @@ static void local_release(struct kref *ref) > > int nfc_llcp_local_put(struct nfc_llcp_local *local) > { > + struct nfc_dev *dev; > + int ret; > + > if (local == NULL) > return 0; > > - return kref_put(&local->ref, local_release); > + dev = local->dev; > + > + ret = kref_put(&local->ref, local_release); > + nfc_put_device(dev); > + > + return ret; > } > > static struct nfc_llcp_sock *nfc_llcp_sock_get(struct nfc_llcp_local *local, > @@ -901,7 +916,7 @@ static void nfc_llcp_recv_connect(struct nfc_llcp_local *local, > > if (dsap != LLCP_SAP_SDP) { > sock = nfc_llcp_sock_get(local, dsap, LLCP_SAP_SDP); > - if (sock == NULL || sock->sk.sk_state != LLCP_LISTEN) { > + if (!sock || sock->sk.sk_state != LLCP_LISTEN) { This is unrelated change. Please keep all cleanups separate from fixes. > reason = LLCP_DM_NOBOUND; > goto fail; > } > @@ -910,7 +925,7 @@ static void nfc_llcp_recv_connect(struct nfc_llcp_local *local, > size_t sn_len; > > sn = nfc_llcp_connect_sn(skb, &sn_len); > - if (sn == NULL) { > + if (!sn) { Not related. > reason = LLCP_DM_NOBOUND; > goto fail; > } > @@ -918,7 +933,7 @@ static void nfc_llcp_recv_connect(struct nfc_llcp_local *local, > pr_debug("Service name length %zu\n", sn_len); > > sock = nfc_llcp_sock_get_sn(local, sn, sn_len); > - if (sock == NULL) { > + if (!sock) { Not related. > reason = LLCP_DM_NOBOUND; > goto fail; > } > @@ -928,39 +943,31 @@ static void nfc_llcp_recv_connect(struct nfc_llcp_local *local, > > parent = &sock->sk; > > - if (sk_acceptq_is_full(parent)) { > - reason = LLCP_DM_REJ; > - release_sock(&sock->sk); > - sock_put(&sock->sk); > - goto fail; > - } > + if (sk_acceptq_is_full(parent)) > + goto fail_put_sock; I would argue that you reshuffle here more code than needed for the fix. This should fix only missing dev reference, not reshuffle code. It's a bugfix, not cleanup. > > if (sock->ssap == LLCP_SDP_UNBOUND) { > u8 ssap = nfc_llcp_reserve_sdp_ssap(local); > > pr_debug("First client, reserving %d\n", ssap); > > - if (ssap == LLCP_SAP_MAX) { > - reason = LLCP_DM_REJ; > - release_sock(&sock->sk); > - sock_put(&sock->sk); > - goto fail; > - } > + if (ssap == LLCP_SAP_MAX) > + goto fail_put_sock; > > sock->ssap = ssap; > } > Best regards, Krzysztof