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 D2C044E3245; Wed, 30 Sep 2026 16:45:27 +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=1790786729; cv=none; b=TkZJEKHMYdRw7GyNd5RQQGNEtFxET69WEV/mWXy+PomYVseA7uMyW3Zeq4y6KPzPuEzIHy8hSN/45Sq2cFGUWpccoWNA440hEldXovVZxza671CIadur1NjvMzATtPVFvohnJEGSSRMTn4j7pVH02cdoFoWwiy0zZX4VWWkMRrM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790786729; c=relaxed/simple; bh=xdqmVw8LWssj/My7VDkKMWSmbN+rmxojQIdy3dmos7U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LzguA4ZNyHn+k0KMjq8/rqSPIP+a/poEZa3euuM+xhO6JJUbfapm/lJKlRU42spZtTjfmQr0SjXd682zgcz9L845xDpMsrnmhLbJWl6MbCLleVQnAlf8tnpngt6EZUIY8l8SRHVocYxv/mVqhmMm1DUPTW9tST+qNaHMrxcT3EE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=GWD0MJQJ; 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="GWD0MJQJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EF2231F000FF; Wed, 30 Sep 2026 16:45:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790786727; bh=cqxTns5nP5xUHJAjAKaZowf8IXA9XC7iA6Pz9anzNx8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=GWD0MJQJNxg0T4s9/cNw8WgVje+HGGv6XSVGHDtw2dzUNTNe1B3F6NkAdPt+2cE2L eppM4yDHCKKZBflBYbMRq0wcYaH3T1jZpjwm7X1/UjulaWP/AD5OORqX4n4MxXVXAW El2uwHVumLlDowcJLD1FgrjTxLMzHXKa6Vhb2MOs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vega , Luxiao Xu , Ren Wei , Simon Horman , David Heidelberg Subject: [PATCH 6.1 963/982] nfc: fix use-after-free in nfc_get_local_general_bytes Date: Wed, 30 Sep 2026 17:28:19 +0200 Message-ID: <20260930152437.427011273@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152416.775402466@linuxfoundation.org> References: <20260930152416.775402466@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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Luxiao Xu commit dcab71a7011918f6fdba7adcec02d217dcb84b8d upstream. Commit 6709d4b7bc2e ("net: nfc: Fix use-after-free caused by nfc_llcp_find_local") attempted to fix a use-after-free (UAF) issue by invoking nfc_llcp_local_put(local) after accessing local->gb. However, if the reference count drops to zero, local is freed immediately, leading to a use-after-free when callers access the returned pointer. Alternative approaches using dynamic allocation (e.g. kmemdup) introduced memory leaks because callers consistently treat the returned pointer as borrowed memory. Fix this properly by refactoring nfc_llcp_general_bytes() and nfc_get_local_general_bytes() to accept a caller-provided output buffer (out_gb) and its maximum length (gb_max_len). The general bytes are safely copied into out_gb before calling nfc_llcp_local_put(local), ensuring safe lifetime management without ownership transfer complications. Update all callers across drivers (microread, pn533, pn544, st21nfca, digital_dep, and nci) to provide their own destination buffers and pass them to nfc_get_local_general_bytes(). Fixes: 6709d4b7bc2e ("net: nfc: Fix use-after-free caused by nfc_llcp_find_local") Cc: stable@vger.kernel.org Reported-by: Vega Assisted-by: LLM Signed-off-by: Luxiao Xu Signed-off-by: Ren Wei Reviewed-by: Simon Horman Link: https://patch.msgid.link/3cbaac3bee23f8ff3a3284ed32d347696eb1d208.1788841683.git.rakukuip@gmail.com Signed-off-by: David Heidelberg Signed-off-by: Greg Kroah-Hartman --- drivers/nfc/microread/microread.c | 6 +++--- drivers/nfc/pn533/pn533.c | 14 ++++++++------ drivers/nfc/pn533/pn533.h | 4 +++- drivers/nfc/pn544/pn544.c | 7 +++---- drivers/nfc/st21nfca/core.c | 8 ++++---- include/net/nfc/hci.h | 2 +- include/net/nfc/nfc.h | 3 ++- net/nfc/core.c | 15 +++++++-------- net/nfc/digital_dep.c | 8 ++++---- net/nfc/llcp_core.c | 17 +++++++++++++---- net/nfc/nci/core.c | 10 +++++----- net/nfc/nfc.h | 3 ++- 12 files changed, 55 insertions(+), 42 deletions(-) --- a/drivers/nfc/microread/microread.c +++ b/drivers/nfc/microread/microread.c @@ -251,9 +251,9 @@ static int microread_start_poll(struct n param[1] |= (1 << 1); if ((im_protocols | tm_protocols) & NFC_PROTO_NFC_DEP_MASK) { - hdev->gb = nfc_get_local_general_bytes(hdev->ndev, - &hdev->gb_len); - if (hdev->gb == NULL || hdev->gb_len == 0) { + nfc_get_local_general_bytes(hdev->ndev, hdev->gb, + sizeof(hdev->gb), &hdev->gb_len); + if (hdev->gb_len == 0) { im_protocols &= ~NFC_PROTO_NFC_DEP_MASK; tm_protocols &= ~NFC_PROTO_NFC_DEP_MASK; } --- a/drivers/nfc/pn533/pn533.c +++ b/drivers/nfc/pn533/pn533.c @@ -1355,10 +1355,11 @@ static int pn533_poll_dep(struct nfc_dev u8 *next, nfcid3[NFC_NFCID3_MAXSIZE]; u8 passive_data[PASSIVE_DATA_LEN] = {0x00, 0xff, 0xff, 0x00, 0x3}; - if (!dev->gb) { - dev->gb = nfc_get_local_general_bytes(nfc_dev, &dev->gb_len); - - if (!dev->gb || !dev->gb_len) { + if (!dev->gb_len) { + nfc_get_local_general_bytes(nfc_dev, dev->gb, + sizeof(dev->gb), + &dev->gb_len); + if (!dev->gb_len) { dev->poll_dep = 0; queue_work(dev->wq, &dev->rf_work); } @@ -1660,8 +1661,9 @@ static int pn533_start_poll(struct nfc_d } if (tm_protocols) { - dev->gb = nfc_get_local_general_bytes(nfc_dev, &dev->gb_len); - if (dev->gb == NULL) + nfc_get_local_general_bytes(nfc_dev, dev->gb, + sizeof(dev->gb), &dev->gb_len); + if (dev->gb_len == 0) tm_protocols = 0; } --- a/drivers/nfc/pn533/pn533.h +++ b/drivers/nfc/pn533/pn533.h @@ -6,6 +6,8 @@ * Copyright (C) 2012-2013 Tieto Poland */ +#include + #define PN533_DEVICE_STD 0x1 #define PN533_DEVICE_PASORI 0x2 #define PN533_DEVICE_ACR122U 0x3 @@ -166,7 +168,7 @@ struct pn533 { struct timer_list listen_timer; int cancel_listen; - u8 *gb; + u8 gb[NFC_MAX_GT_LEN]; size_t gb_len; u8 tgt_available_prots; --- a/drivers/nfc/pn544/pn544.c +++ b/drivers/nfc/pn544/pn544.c @@ -377,10 +377,9 @@ static int pn544_hci_start_poll(struct n return r; if ((im_protocols | tm_protocols) & NFC_PROTO_NFC_DEP_MASK) { - hdev->gb = nfc_get_local_general_bytes(hdev->ndev, - &hdev->gb_len); - pr_debug("generate local bytes %p\n", hdev->gb); - if (hdev->gb == NULL || hdev->gb_len == 0) { + nfc_get_local_general_bytes(hdev->ndev, hdev->gb, + sizeof(hdev->gb), &hdev->gb_len); + if (hdev->gb_len == 0) { im_protocols &= ~NFC_PROTO_NFC_DEP_MASK; tm_protocols &= ~NFC_PROTO_NFC_DEP_MASK; } --- a/drivers/nfc/st21nfca/core.c +++ b/drivers/nfc/st21nfca/core.c @@ -351,10 +351,10 @@ static int st21nfca_hci_start_poll(struc if (r < 0) return r; } else { - hdev->gb = nfc_get_local_general_bytes(hdev->ndev, - &hdev->gb_len); - - if (hdev->gb == NULL || hdev->gb_len == 0) { + nfc_get_local_general_bytes(hdev->ndev, hdev->gb, + sizeof(hdev->gb), + &hdev->gb_len); + if (hdev->gb_len == 0) { im_protocols &= ~NFC_PROTO_NFC_DEP_MASK; tm_protocols &= ~NFC_PROTO_NFC_DEP_MASK; } --- a/include/net/nfc/hci.h +++ b/include/net/nfc/hci.h @@ -144,7 +144,7 @@ struct nfc_hci_dev { data_exchange_cb_t async_cb; void *async_cb_context; - u8 *gb; + u8 gb[NFC_MAX_GT_LEN]; size_t gb_len; unsigned long quirks; --- a/include/net/nfc/nfc.h +++ b/include/net/nfc/nfc.h @@ -269,7 +269,8 @@ struct sk_buff *nfc_alloc_recv_skb(unsig int nfc_set_remote_general_bytes(struct nfc_dev *dev, const u8 *gt, u8 gt_len); -u8 *nfc_get_local_general_bytes(struct nfc_dev *dev, size_t *gb_len); +u8 *nfc_get_local_general_bytes(struct nfc_dev *dev, u8 *out_gb, + size_t gb_max_len, size_t *gb_len); int nfc_fw_download_done(struct nfc_dev *dev, const char *firmware_name, u32 result); --- a/net/nfc/core.c +++ b/net/nfc/core.c @@ -279,10 +279,10 @@ static struct nfc_target *nfc_find_targe int nfc_dep_link_up(struct nfc_dev *dev, int target_index, u8 comm_mode) { - int rc = 0; - u8 *gb; - size_t gb_len; struct nfc_target *target; + u8 gb[NFC_MAX_GT_LEN]; + size_t gb_len = 0; + int rc = 0; pr_debug("dev_name=%s comm %d\n", dev_name(&dev->dev), comm_mode); @@ -301,7 +301,7 @@ int nfc_dep_link_up(struct nfc_dev *dev, goto error; } - gb = nfc_llcp_general_bytes(dev, &gb_len); + nfc_get_local_general_bytes(dev, gb, sizeof(gb), &gb_len); if (gb_len > NFC_MAX_GT_LEN) { rc = -EINVAL; goto error; @@ -644,11 +644,10 @@ int nfc_set_remote_general_bytes(struct } EXPORT_SYMBOL(nfc_set_remote_general_bytes); -u8 *nfc_get_local_general_bytes(struct nfc_dev *dev, size_t *gb_len) +u8 *nfc_get_local_general_bytes(struct nfc_dev *dev, u8 *out_gb, + size_t gb_max_len, size_t *gb_len) { - pr_debug("dev_name=%s\n", dev_name(&dev->dev)); - - return nfc_llcp_general_bytes(dev, gb_len); + return nfc_llcp_general_bytes(dev, out_gb, gb_max_len, gb_len); } EXPORT_SYMBOL(nfc_get_local_general_bytes); --- a/net/nfc/digital_dep.c +++ b/net/nfc/digital_dep.c @@ -1490,14 +1490,14 @@ static int digital_tg_send_atr_res(struc struct digital_atr_req *atr_req) { struct digital_atr_res *atr_res; + u8 gb[NFC_MAX_GT_LEN]; struct sk_buff *skb; - u8 *gb, payload_bits; + u8 payload_bits; size_t gb_len; int rc; - gb = nfc_get_local_general_bytes(ddev->nfc_dev, &gb_len); - if (!gb) - gb_len = 0; + nfc_get_local_general_bytes(ddev->nfc_dev, gb, sizeof(gb), + &gb_len); skb = digital_skb_alloc(ddev, sizeof(struct digital_atr_res) + gb_len); if (!skb) --- a/net/nfc/llcp_core.c +++ b/net/nfc/llcp_core.c @@ -651,23 +651,32 @@ out: return ret; } -u8 *nfc_llcp_general_bytes(struct nfc_dev *dev, size_t *general_bytes_len) +u8 *nfc_llcp_general_bytes(struct nfc_dev *dev, u8 *out_gb, size_t gb_max_len, + size_t *general_bytes_len) { struct nfc_llcp_local *local; + if (!out_gb || !general_bytes_len) + return NULL; + local = nfc_llcp_find_local(dev); - if (local == NULL) { + if (!local) { *general_bytes_len = 0; return NULL; } nfc_llcp_build_gb(local); - *general_bytes_len = local->gb_len; + if (local->gb_len) { + *general_bytes_len = min_t(size_t, local->gb_len, gb_max_len); + memcpy(out_gb, local->gb, *general_bytes_len); + } else { + *general_bytes_len = 0; + } nfc_llcp_local_put(local); - return local->gb; + return out_gb; } int nfc_llcp_set_remote_gb(struct nfc_dev *dev, const u8 *gb, u8 gb_len) --- a/net/nfc/nci/core.c +++ b/net/nfc/nci/core.c @@ -762,15 +762,15 @@ static int nci_set_local_general_bytes(s { struct nci_dev *ndev = nfc_get_drvdata(nfc_dev); struct nci_set_config_param param; + u8 gb[NFC_MAX_GT_LEN]; int rc; - param.val = nfc_get_local_general_bytes(nfc_dev, ¶m.len); - if ((param.val == NULL) || (param.len == 0)) + nfc_get_local_general_bytes(nfc_dev, gb, sizeof(gb), + ¶m.len); + if (param.len == 0) return 0; - if (param.len > NFC_MAX_GT_LEN) - return -EINVAL; - + param.val = gb; param.id = NCI_PN_ATR_REQ_GEN_BYTES; rc = nci_request(ndev, nci_set_config_req, ¶m, --- a/net/nfc/nfc.h +++ b/net/nfc/nfc.h @@ -49,7 +49,8 @@ void nfc_llcp_mac_is_up(struct nfc_dev * int nfc_llcp_register_device(struct nfc_dev *dev); void nfc_llcp_unregister_device(struct nfc_dev *dev); int nfc_llcp_set_remote_gb(struct nfc_dev *dev, const u8 *gb, u8 gb_len); -u8 *nfc_llcp_general_bytes(struct nfc_dev *dev, size_t *general_bytes_len); +u8 *nfc_llcp_general_bytes(struct nfc_dev *dev, u8 *out_gb, size_t gb_max_len, + size_t *general_bytes_len); int nfc_llcp_data_received(struct nfc_dev *dev, struct sk_buff *skb); struct nfc_llcp_local *nfc_llcp_find_local(struct nfc_dev *dev); int nfc_llcp_local_put(struct nfc_llcp_local *local);