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 8037CC43334 for ; Mon, 13 Jun 2022 14:51:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1386162AbiFMOvc (ORCPT ); Mon, 13 Jun 2022 10:51:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1385823AbiFMOsm (ORCPT ); Mon, 13 Jun 2022 10:48:42 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95FEAC0472; Mon, 13 Jun 2022 04:52:57 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5703B61499; Mon, 13 Jun 2022 11:52:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B8896C34114; Mon, 13 Jun 2022 11:52:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1655121176; bh=G0vA+oHO6Pf/NwOimi2XtgklJgsVBvKZSqkj2BqgjLQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=u5y836JwH7Yo4aKFTe7zemqJ/LQtrmSDCtEUZjxgtcNY5YknVWKxXU9/hReL9oXx/ PhszAcAbOFojZMzSDfehvIPVFHRY9ISQZkWjDSfwgj5cfvTZ096WgC7QjTyf87IWAl OTjZStEAogY/B+6wZqvwvxHZPBxuK5kucHLzu8oo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Martin Faltesek , Guenter Roeck , Krzysztof Kozlowski , Jakub Kicinski Subject: [PATCH 5.17 276/298] nfc: st21nfca: fix incorrect sizing calculations in EVT_TRANSACTION Date: Mon, 13 Jun 2022 12:12:50 +0200 Message-Id: <20220613094933.449084975@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220613094924.913340374@linuxfoundation.org> References: <20220613094924.913340374@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Martin Faltesek commit f2e19b36593caed4c977c2f55aeba7408aeb2132 upstream. The transaction buffer is allocated by using the size of the packet buf, and subtracting two which seem intended to remove the two tags which are not present in the target structure. This calculation leads to under counting memory because of differences between the packet contents and the target structure. The aid_len field is a u8 in the packet, but a u32 in the structure, resulting in at least 3 bytes always being under counted. Further, the aid data is a variable length field in the packet, but fixed in the structure, so if this field is less than the max, the difference is added to the under counting. The last validation check for transaction->params_len is also incorrect since it employs the same accounting error. To fix, perform validation checks progressively to safely reach the next field, to determine the size of both buffers and verify both tags. Once all validation checks pass, allocate the buffer and copy the data. This eliminates freeing memory on the error path, as those checks are moved ahead of memory allocation. Fixes: 26fc6c7f02cb ("NFC: st21nfca: Add HCI transaction event support") Fixes: 4fbcc1a4cb20 ("nfc: st21nfca: Fix potential buffer overflows in EVT_TRANSACTION") Cc: stable@vger.kernel.org Signed-off-by: Martin Faltesek Reviewed-by: Guenter Roeck Reviewed-by: Krzysztof Kozlowski Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/nfc/st21nfca/se.c | 62 +++++++++++++++++++++++----------------------- 1 file changed, 31 insertions(+), 31 deletions(-) --- a/drivers/nfc/st21nfca/se.c +++ b/drivers/nfc/st21nfca/se.c @@ -300,6 +300,8 @@ int st21nfca_connectivity_event_received int r = 0; struct device *dev = &hdev->ndev->dev; struct nfc_evt_transaction *transaction; + u32 aid_len; + u8 params_len; pr_debug("connectivity gate event: %x\n", event); @@ -308,50 +310,48 @@ int st21nfca_connectivity_event_received r = nfc_se_connectivity(hdev->ndev, host); break; case ST21NFCA_EVT_TRANSACTION: - /* - * According to specification etsi 102 622 + /* According to specification etsi 102 622 * 11.2.2.4 EVT_TRANSACTION Table 52 * Description Tag Length * AID 81 5 to 16 * PARAMETERS 82 0 to 255 + * + * The key differences are aid storage length is variably sized + * in the packet, but fixed in nfc_evt_transaction, and that the aid_len + * is u8 in the packet, but u32 in the structure, and the tags in + * the packet are not included in nfc_evt_transaction. + * + * size in bytes: 1 1 5-16 1 1 0-255 + * offset: 0 1 2 aid_len + 2 aid_len + 3 aid_len + 4 + * member name: aid_tag(M) aid_len aid params_tag(M) params_len params + * example: 0x81 5-16 X 0x82 0-255 X */ - if (skb->len < NFC_MIN_AID_LENGTH + 2 || - skb->data[0] != NFC_EVT_TRANSACTION_AID_TAG) + if (skb->len < 2 || skb->data[0] != NFC_EVT_TRANSACTION_AID_TAG) return -EPROTO; - transaction = devm_kzalloc(dev, skb->len - 2, GFP_KERNEL); - if (!transaction) - return -ENOMEM; + aid_len = skb->data[1]; + + if (skb->len < aid_len + 4 || aid_len > sizeof(transaction->aid)) + return -EPROTO; - transaction->aid_len = skb->data[1]; + params_len = skb->data[aid_len + 3]; - /* Checking if the length of the AID is valid */ - if (transaction->aid_len > sizeof(transaction->aid)) { - devm_kfree(dev, transaction); - return -EINVAL; - } - - memcpy(transaction->aid, &skb->data[2], - transaction->aid_len); - - /* Check next byte is PARAMETERS tag (82) */ - if (skb->data[transaction->aid_len + 2] != - NFC_EVT_TRANSACTION_PARAMS_TAG) { - devm_kfree(dev, transaction); + /* Verify PARAMETERS tag is (82), and final check that there is enough + * space in the packet to read everything. + */ + if ((skb->data[aid_len + 2] != NFC_EVT_TRANSACTION_PARAMS_TAG) || + (skb->len < aid_len + 4 + params_len)) return -EPROTO; - } - transaction->params_len = skb->data[transaction->aid_len + 3]; + transaction = devm_kzalloc(dev, sizeof(*transaction) + params_len, GFP_KERNEL); + if (!transaction) + return -ENOMEM; - /* Total size is allocated (skb->len - 2) minus fixed array members */ - if (transaction->params_len > ((skb->len - 2) - - sizeof(struct nfc_evt_transaction))) { - devm_kfree(dev, transaction); - return -EINVAL; - } + transaction->aid_len = aid_len; + transaction->params_len = params_len; - memcpy(transaction->params, skb->data + - transaction->aid_len + 4, transaction->params_len); + memcpy(transaction->aid, &skb->data[2], aid_len); + memcpy(transaction->params, &skb->data[aid_len + 4], params_len); r = nfc_se_transaction(hdev->ndev, host, transaction); break;