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(118-163-61-247.hinet-ip.hinet.net. [118.163.61.247]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7254176150dsm357506b3a.23.2024.11.27.19.08.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Nov 2024 19:08:10 -0800 (PST) From: En-Wei Wu To: marcel@holtmann.org, luiz.dentz@gmail.com, linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org Cc: anthony.wong@canonical.com, kuan-ying.lee@canonical.com Subject: [PATCH] Bluetooth: btusb: avoid NULL pointer defereference in skb_dequeue() Date: Thu, 28 Nov 2024 11:08:07 +0800 Message-ID: <20241128030807.270581-1-en-wei.wu@canonical.com> X-Mailer: git-send-email 2.43.0 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" The WCN7851 (0489:e0f3) Bluetooth controller supports firmware crash dump collection through devcoredump. During this process, the crash dump data is queued to a dump queue as skb for further processing. A NULL pointer dereference occurs in skb_dequeue() when processing the dump queue due to improper return value handling: [ 93.672166] Bluetooth: hci0: ACL memdump size(589824) [ 93.672475] BUG: kernel NULL pointer dereference, address: 0000000000000008 [ 93.672517] Workqueue: hci0 hci_devcd_rx [bluetooth] [ 93.672598] RIP: 0010:skb_dequeue+0x50/0x80 The issue stems from handle_dump_pkt_qca() returning the wrong value on success. It currently returns the value from hci_devcd_init() (0 on success= ), but callers expect > 0 to indicate successful dump handling. This causes hci_recv_frame() to free the skb while it's still queued for dump processing, leading to the NULL pointer dereference when hci_devcd_rx() tries to dequeue it. Fix this by: 1. Extracting dump packet detection into new is_dump_pkt_qca() function 2. Making handle_dump_pkt_qca() return 0 on success and negative errno on failure, consistent with other kernel interfaces This prevents premature skb freeing by ensuring proper handling of dump pac= kets. Fixes: 20981ce2d5a5 ("Bluetooth: btusb: Add WCN6855 devcoredump support") Signed-off-by: En-Wei Wu --- drivers/bluetooth/btusb.c | 75 ++++++++++++++++++++++++--------------- 1 file changed, 47 insertions(+), 28 deletions(-) diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c index 279fe6c115fa..8926f8f60e5c 100644 --- a/drivers/bluetooth/btusb.c +++ b/drivers/bluetooth/btusb.c @@ -2930,22 +2930,16 @@ static void btusb_coredump_qca(struct hci_dev *hdev) bt_dev_err(hdev, "%s: triggle crash failed (%d)", __func__, err); } =20 -/* - * =3D=3D0: not a dump pkt. - * < 0: fails to handle a dump pkt - * > 0: otherwise. - */ +/* Return: 0 on success, negative errno on failure. */ static int handle_dump_pkt_qca(struct hci_dev *hdev, struct sk_buff *skb) { - int ret =3D 1; + int ret =3D 0; u8 pkt_type; u8 *sk_ptr; unsigned int sk_len; u16 seqno; u32 dump_size; =20 - struct hci_event_hdr *event_hdr; - struct hci_acl_hdr *acl_hdr; struct qca_dump_hdr *dump_hdr; struct btusb_data *btdata =3D hci_get_drvdata(hdev); struct usb_device *udev =3D btdata->udev; @@ -2955,30 +2949,14 @@ static int handle_dump_pkt_qca(struct hci_dev *hdev= , struct sk_buff *skb) sk_len =3D skb->len; =20 if (pkt_type =3D=3D HCI_ACLDATA_PKT) { - acl_hdr =3D hci_acl_hdr(skb); - if (le16_to_cpu(acl_hdr->handle) !=3D QCA_MEMDUMP_ACL_HANDLE) - return 0; sk_ptr +=3D HCI_ACL_HDR_SIZE; sk_len -=3D HCI_ACL_HDR_SIZE; - event_hdr =3D (struct hci_event_hdr *)sk_ptr; - } else { - event_hdr =3D hci_event_hdr(skb); } =20 - if ((event_hdr->evt !=3D HCI_VENDOR_PKT) - || (event_hdr->plen !=3D (sk_len - HCI_EVENT_HDR_SIZE))) - return 0; - sk_ptr +=3D HCI_EVENT_HDR_SIZE; sk_len -=3D HCI_EVENT_HDR_SIZE; =20 dump_hdr =3D (struct qca_dump_hdr *)sk_ptr; - if ((sk_len < offsetof(struct qca_dump_hdr, data)) - || (dump_hdr->vse_class !=3D QCA_MEMDUMP_VSE_CLASS) - || (dump_hdr->msg_type !=3D QCA_MEMDUMP_MSG_TYPE)) - return 0; - - /*it is dump pkt now*/ seqno =3D le16_to_cpu(dump_hdr->seqno); if (seqno =3D=3D 0) { set_bit(BTUSB_HW_SSR_ACTIVE, &btdata->flags); @@ -3052,17 +3030,58 @@ static int handle_dump_pkt_qca(struct hci_dev *hdev= , struct sk_buff *skb) return ret; } =20 +/* Return: true if packet is a dump packet, false otherwise. */ +static bool is_dump_pkt_qca(struct hci_dev *hdev, struct sk_buff *skb) +{ + u8 pkt_type; + u8 *sk_ptr; + unsigned int sk_len; + + struct hci_event_hdr *event_hdr; + struct hci_acl_hdr *acl_hdr; + struct qca_dump_hdr *dump_hdr; + + pkt_type =3D hci_skb_pkt_type(skb); + sk_ptr =3D skb->data; + sk_len =3D skb->len; + + if (pkt_type =3D=3D HCI_ACLDATA_PKT) { + acl_hdr =3D hci_acl_hdr(skb); + if (le16_to_cpu(acl_hdr->handle) !=3D QCA_MEMDUMP_ACL_HANDLE) + return false; + sk_ptr +=3D HCI_ACL_HDR_SIZE; + sk_len -=3D HCI_ACL_HDR_SIZE; + event_hdr =3D (struct hci_event_hdr *)sk_ptr; + } else { + event_hdr =3D hci_event_hdr(skb); + } + + if ((event_hdr->evt !=3D HCI_VENDOR_PKT) + || (event_hdr->plen !=3D (sk_len - HCI_EVENT_HDR_SIZE))) + return false; + + sk_ptr +=3D HCI_EVENT_HDR_SIZE; + sk_len -=3D HCI_EVENT_HDR_SIZE; + + dump_hdr =3D (struct qca_dump_hdr *)sk_ptr; + if ((sk_len < offsetof(struct qca_dump_hdr, data)) + || (dump_hdr->vse_class !=3D QCA_MEMDUMP_VSE_CLASS) + || (dump_hdr->msg_type !=3D QCA_MEMDUMP_MSG_TYPE)) + return false; + + return true; +} static int btusb_recv_acl_qca(struct hci_dev *hdev, struct sk_buff *skb) { - if (handle_dump_pkt_qca(hdev, skb)) - return 0; + if (is_dump_pkt_qca(hdev, skb)) + return handle_dump_pkt_qca(hdev, skb); return hci_recv_frame(hdev, skb); } =20 static int btusb_recv_evt_qca(struct hci_dev *hdev, struct sk_buff *skb) { - if (handle_dump_pkt_qca(hdev, skb)) - return 0; + if (is_dump_pkt_qca(hdev, skb)) + return handle_dump_pkt_qca(hdev, skb); return hci_recv_frame(hdev, skb); } =20 --=20 2.43.0