[PATCH v1 1/2] Bluetooth: Fix NULL pointer deference on eir_get_service_data

[Luiz Augusto von Dentz <luiz.dentz@xxxxxxxxx>]

From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>

The len parameter is considered optional so it can be NULL so it cannot
be used for skipping to next entry of EIR_SERVICE_DATA.

Fixes: 8f9ae5b3ae80 ("Bluetooth: eir: Add helpers for managing service data")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
---
 net/bluetooth/eir.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/net/bluetooth/eir.c b/net/bluetooth/eir.c
index 1bc51e2b05a3..3e1713673ecc 100644
--- a/net/bluetooth/eir.c
+++ b/net/bluetooth/eir.c
@@ -366,17 +366,19 @@ u8 eir_create_scan_rsp(struct hci_dev *hdev, u8 instance, u8 *ptr)
 
 void *eir_get_service_data(u8 *eir, size_t eir_len, u16 uuid, size_t *len)
 {
-	while ((eir = eir_get_data(eir, eir_len, EIR_SERVICE_DATA, len))) {
+	size_t dlen;
+
+	while ((eir = eir_get_data(eir, eir_len, EIR_SERVICE_DATA, &dlen))) {
 		u16 value = get_unaligned_le16(eir);
 
 		if (uuid == value) {
 			if (len)
-				*len -= 2;
+				*len = dlen - 2;
 			return &eir[2];
 		}
 
-		eir += *len;
-		eir_len -= *len;
+		eir += dlen;
+		eir_len -= dlen;
 	}
 
 	return NULL;
-- 
2.49.0