linux-kernel - [PATCH 5.17 0630/1126] Bluetooth: Fix skb allocation in mgmt_remote_name() & mgmt_device

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Message-Id: <20220405070426.128609733@linuxfoundation.org>
Date:   Tue,  5 Apr 2022 09:22:57 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Angela Czubak <acz@...ihalf.com>,
        Marek Maslanka <mm@...ihalf.com>,
        Radoslaw Biernacki <rad@...ihalf.com>,
        Luiz Augusto von Dentz <luiz.von.dentz@...el.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.17 0630/1126] Bluetooth: Fix skb allocation in mgmt_remote_name() & mgmt_device_connected()

From: Radoslaw Biernacki <rad@...ihalf.com>

[ Upstream commit ba17bb62ce415950753c19d16bb43b2bd3701158 ]

This patch fixes skb allocation, as lack of space for ev might push skb
tail beyond its end.
Also introduce eir_precalc_len() that can be used instead of magic
numbers for similar eir operations on skb.

Fixes: cf1bce1de7eeb ("Bluetooth: mgmt: Make use of mgmt_send_event_skb in MGMT_EV_DEVICE_FOUND")
Fixes: e96741437ef0a ("Bluetooth: mgmt: Make use of mgmt_send_event_skb in MGMT_EV_DEVICE_CONNECTED")
Signed-off-by: Angela Czubak <acz@...ihalf.com>
Signed-off-by: Marek Maslanka <mm@...ihalf.com>
Signed-off-by: Radoslaw Biernacki <rad@...ihalf.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/bluetooth/eir.h  |  5 +++++
 net/bluetooth/mgmt.c | 18 ++++++++----------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/net/bluetooth/eir.h b/net/bluetooth/eir.h
index 05e2e917fc25..e5876751f07e 100644
--- a/net/bluetooth/eir.h
+++ b/net/bluetooth/eir.h
@@ -15,6 +15,11 @@ u8 eir_create_scan_rsp(struct hci_dev *hdev, u8 instance, u8 *ptr);
 u8 eir_append_local_name(struct hci_dev *hdev, u8 *eir, u8 ad_len);
 u8 eir_append_appearance(struct hci_dev *hdev, u8 *ptr, u8 ad_len);
 
+static inline u16 eir_precalc_len(u8 data_len)
+{
+	return sizeof(u8) * 2 + data_len;
+}
+
 static inline u16 eir_append_data(u8 *eir, u16 eir_len, u8 type,
 				  u8 *data, u8 data_len)
 {
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 230a7a8196c0..15eab8b968ce 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -9086,12 +9086,14 @@ void mgmt_device_connected(struct hci_dev *hdev, struct hci_conn *conn,
 	u16 eir_len = 0;
 	u32 flags = 0;
 
+	/* allocate buff for LE or BR/EDR adv */
 	if (conn->le_adv_data_len > 0)
 		skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_CONNECTED,
-				     conn->le_adv_data_len);
+				     sizeof(*ev) + conn->le_adv_data_len);
 	else
 		skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_CONNECTED,
-				     2 + name_len + 5);
+				     sizeof(*ev) + (name ? eir_precalc_len(name_len) : 0) +
+				     eir_precalc_len(sizeof(conn->dev_class)));
 
 	ev = skb_put(skb, sizeof(*ev));
 	bacpy(&ev->addr.bdaddr, &conn->dst);
@@ -9707,13 +9709,11 @@ void mgmt_remote_name(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
 {
 	struct sk_buff *skb;
 	struct mgmt_ev_device_found *ev;
-	u16 eir_len;
-	u32 flags;
+	u16 eir_len = 0;
+	u32 flags = 0;
 
-	if (name_len)
-		skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND, 2 + name_len);
-	else
-		skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND, 0);
+	skb = mgmt_alloc_skb(hdev, MGMT_EV_DEVICE_FOUND,
+			     sizeof(*ev) + (name ? eir_precalc_len(name_len) : 0));
 
 	ev = skb_put(skb, sizeof(*ev));
 	bacpy(&ev->addr.bdaddr, bdaddr);
@@ -9723,10 +9723,8 @@ void mgmt_remote_name(struct hci_dev *hdev, bdaddr_t *bdaddr, u8 link_type,
 	if (name) {
 		eir_len = eir_append_data(ev->eir, 0, EIR_NAME_COMPLETE, name,
 					  name_len);
-		flags = 0;
 		skb_put(skb, eir_len);
 	} else {
-		eir_len = 0;
 		flags = MGMT_DEV_FOUND_NAME_REQUEST_FAILED;
 	}
 
-- 
2.34.1