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From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Danis?= <frederic.danis@collabora.com>
To: linux-bluetooth@vger.kernel.org
Subject: [PATCH BlueZ] Bluetooth: Fix eir name length
Date: Thu,  7 Mar 2024 17:42:05 +0100
Message-Id: <20240307164205.1011133-1-frederic.danis@collabora.com>
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According to Section 1.2 of Core Specification Supplement Part A the
complete or short name strings are defined as utf8s, which should not
include the trailing NULL for variable length array as defined in Core
Specification Vol1 Part E Section 2.9.3.

The trailing NULL was introduce by commit f61851f64b17
("Bluetooth: Fix append max 11 bytes of name to scan rsp data")

Removing the trailing NULL allows PTS to retrieve the random address based
on device name, e.g. for SM/PER/KDU/BV-02-C, SM/PER/KDU/BV-08-C or
GAP/BROB/BCST/BV-03-C.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>
---
 net/bluetooth/eir.c  | 29 +++++++----------------------
 net/bluetooth/mgmt.c |  2 +-
 2 files changed, 8 insertions(+), 23 deletions(-)

diff --git a/net/bluetooth/eir.c b/net/bluetooth/eir.c
index 9214189279e8..1bc51e2b05a3 100644
--- a/net/bluetooth/eir.c
+++ b/net/bluetooth/eir.c
@@ -13,48 +13,33 @@
 
 #define PNP_INFO_SVCLASS_ID		0x1200
 
-static u8 eir_append_name(u8 *eir, u16 eir_len, u8 type, u8 *data, u8 data_len)
-{
-	u8 name[HCI_MAX_SHORT_NAME_LENGTH + 1];
-
-	/* If data is already NULL terminated just pass it directly */
-	if (data[data_len - 1] == '\0')
-		return eir_append_data(eir, eir_len, type, data, data_len);
-
-	memcpy(name, data, HCI_MAX_SHORT_NAME_LENGTH);
-	name[HCI_MAX_SHORT_NAME_LENGTH] = '\0';
-
-	return eir_append_data(eir, eir_len, type, name, sizeof(name));
-}
-
 u8 eir_append_local_name(struct hci_dev *hdev, u8 *ptr, u8 ad_len)
 {
 	size_t short_len;
 	size_t complete_len;
 
-	/* no space left for name (+ NULL + type + len) */
-	if ((max_adv_len(hdev) - ad_len) < HCI_MAX_SHORT_NAME_LENGTH + 3)
+	/* no space left for name (+ type + len) */
+	if ((max_adv_len(hdev) - ad_len) < HCI_MAX_SHORT_NAME_LENGTH + 2)
 		return ad_len;
 
 	/* use complete name if present and fits */
 	complete_len = strnlen(hdev->dev_name, sizeof(hdev->dev_name));
 	if (complete_len && complete_len <= HCI_MAX_SHORT_NAME_LENGTH)
-		return eir_append_name(ptr, ad_len, EIR_NAME_COMPLETE,
-				       hdev->dev_name, complete_len + 1);
+		return eir_append_data(ptr, ad_len, EIR_NAME_COMPLETE,
+				       hdev->dev_name, complete_len);
 
 	/* use short name if present */
 	short_len = strnlen(hdev->short_name, sizeof(hdev->short_name));
 	if (short_len)
-		return eir_append_name(ptr, ad_len, EIR_NAME_SHORT,
+		return eir_append_data(ptr, ad_len, EIR_NAME_SHORT,
 				       hdev->short_name,
-				       short_len == HCI_MAX_SHORT_NAME_LENGTH ?
-				       short_len : short_len + 1);
+				       short_len);
 
 	/* use shortened full name if present, we already know that name
 	 * is longer then HCI_MAX_SHORT_NAME_LENGTH
 	 */
 	if (complete_len)
-		return eir_append_name(ptr, ad_len, EIR_NAME_SHORT,
+		return eir_append_data(ptr, ad_len, EIR_NAME_SHORT,
 				       hdev->dev_name,
 				       HCI_MAX_SHORT_NAME_LENGTH);
 
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 9613cc8a60f8..32ed6e9245a3 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -8408,7 +8408,7 @@ static int read_adv_features(struct sock *sk, struct hci_dev *hdev,
 
 static u8 calculate_name_len(struct hci_dev *hdev)
 {
-	u8 buf[HCI_MAX_SHORT_NAME_LENGTH + 3];
+	u8 buf[HCI_MAX_SHORT_NAME_LENGTH + 2]; /* len + type + name */
 
 	return eir_append_local_name(hdev, buf, 0);
 }
-- 
2.34.1