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Wed, 10 Jun 2026 01:17:22 -0700 (PDT) Received: from secrnd-cstp.tailb7f510.ts.net ([125.131.91.97]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-84282916b10sm23929773b3a.58.2026.06.10.01.17.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Jun 2026 01:17:21 -0700 (PDT) From: Sanghyun Park To: krzk@kernel.org Cc: Sanghyun Park , davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, 681739313@139.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net v2] nfc: nci: Fix use-after-free on conn_info in nci_tx_work() Date: Wed, 10 Jun 2026 17:16:57 +0900 Message-ID: <20260610081657.686636-1-sanghyun.park.cnu@gmail.com> X-Mailer: git-send-email 2.48.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" nci_tx_work() looks up conn_info from conn_info_list and keeps using that pointer while sending queued data. nci_core_conn_close_rsp_packet() runs on the separate rx_wq and can remove and free the same conn_info, so the tx worker can dereference freed memory. Race: CPU0 (tx_wq) CPU1 (rx_wq) =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D nci_tx_work() conn_info =3D nci_get_conn_info_by_conn_id() nci_core_conn_close_rsp_packet() list_del(&conn_info->list) devm_kfree(conn_info) atomic_read(&conn_info->credits_cnt) // UAF: conn_info was freed by CPU1 Protect conn_info_list with a dedicated conn_lock while nci_tx_work() uses conn_info and while nci_core_conn_close_rsp_packet() removes and frees it. This makes close wait for any in-flight tx worker before freeing the entry, and makes later tx workers observe that the entry is already gone. Signed-off-by: Sanghyun Park --- v2: - Replace flush-only fix with conn_lock protection v1: https://patchwork.kernel.org/project/netdevbpf/patch/CAOrxSK5UmFFfzdRG+= P89+E+Rvg_1DmOvTs+M7353Q8=3DhkPXmSg@mail.gmail.com/ include/net/nfc/nci_core.h | 1 + net/nfc/nci/core.c | 9 +++++++-- net/nfc/nci/rsp.c | 2 ++ 3 files changed, 10 insertions(+), 2 deletions(-) diff --git a/include/net/nfc/nci_core.h b/include/net/nfc/nci_core.h index e066bdbc807..22b245bc17c 100644 --- a/include/net/nfc/nci_core.h +++ b/include/net/nfc/nci_core.h @@ -227,6 +227,7 @@ struct nci_dev { struct sk_buff_head tx_q; =20 struct mutex req_lock; + struct mutex conn_lock; struct completion req_completion; __u32 req_status; __u32 req_result; diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c index 058d4eb530f..a24b9703115 100644 --- a/net/nfc/nci/core.c +++ b/net/nfc/nci/core.c @@ -1277,6 +1277,7 @@ int nci_register_device(struct nci_dev *ndev) timer_setup(&ndev->data_timer, nci_data_timer, 0); =20 mutex_init(&ndev->req_lock); + mutex_init(&ndev->conn_lock); INIT_LIST_HEAD(&ndev->conn_info_list); =20 rc =3D nfc_register_device(ndev->nfc_dev); @@ -1512,9 +1513,10 @@ static void nci_tx_work(struct work_struct *work) struct nci_conn_info *conn_info; struct sk_buff *skb; =20 + mutex_lock(&ndev->conn_lock); conn_info =3D nci_get_conn_info_by_conn_id(ndev, ndev->cur_conn_id); if (!conn_info) - return; + goto unlock; =20 pr_debug("credits_cnt %d\n", atomic_read(&conn_info->credits_cnt)); =20 @@ -1522,7 +1524,7 @@ static void nci_tx_work(struct work_struct *work) while (atomic_read(&conn_info->credits_cnt)) { skb =3D skb_dequeue(&ndev->tx_q); if (!skb) - return; + goto unlock; kcov_remote_start_common(skb_get_kcov_handle(skb)); =20 /* Check if data flow control is used */ @@ -1541,6 +1543,9 @@ static void nci_tx_work(struct work_struct *work) jiffies + msecs_to_jiffies(NCI_DATA_TIMEOUT)); kcov_remote_stop(); } + +unlock: + mutex_unlock(&ndev->conn_lock); } =20 /* ----- NCI RX worker thread (data & control) ----- */ diff --git a/net/nfc/nci/rsp.c b/net/nfc/nci/rsp.c index b911ab78bed..dfebf1ed945 100644 --- a/net/nfc/nci/rsp.c +++ b/net/nfc/nci/rsp.c @@ -330,6 +330,7 @@ static void nci_core_conn_close_rsp_packet(struct nci_d= ev *ndev, =20 pr_debug("status 0x%x\n", status); if (status =3D=3D NCI_STATUS_OK) { + mutex_lock(&ndev->conn_lock); conn_info =3D nci_get_conn_info_by_conn_id(ndev, ndev->cur_conn_id); if (conn_info) { @@ -338,6 +339,7 @@ static void nci_core_conn_close_rsp_packet(struct nci_d= ev *ndev, ndev->rf_conn_info =3D NULL; devm_kfree(&ndev->nfc_dev->dev, conn_info); } + mutex_unlock(&ndev->conn_lock); } nci_req_complete(ndev, status); } --=20 2.48.1