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nimble/host: Fix possible overflow in ble_gatts_peer_cl_sup_feat_update #1671

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merged 1 commit into from
Jan 9, 2024
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nimble/host: Fix possible overflow in ble_gatts_peer_cl_sup_feat_update #1671

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59 changes: 28 additions & 31 deletions nimble/host/src/ble_gatts.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1613,8 +1613,9 @@ int
ble_gatts_peer_cl_sup_feat_update(uint16_t conn_handle, struct os_mbuf *om)
{
struct ble_hs_conn *conn;
uint8_t feat[BLE_GATT_CHR_CLI_SUP_FEAT_SZ] = {};
uint16_t len;
int rc = 0;
int feat_idx = 0;
int i;

BLE_HS_LOG(DEBUG, "");
Expand All @@ -1623,46 +1624,42 @@ ble_gatts_peer_cl_sup_feat_update(uint16_t conn_handle, struct os_mbuf *om)
return BLE_ATT_ERR_INSUFFICIENT_RES;
}

/* RFU bits are ignored so we can skip any bytes larger than supported */
len = os_mbuf_len(om);
if (len > BLE_GATT_CHR_CLI_SUP_FEAT_SZ) {
len = BLE_GATT_CHR_CLI_SUP_FEAT_SZ;
}

if (os_mbuf_copydata(om, 0, len, feat) < 0) {
return BLE_ATT_ERR_UNLIKELY;
}

/* clear RFU bits */
for (i = 0; i < BLE_GATT_CHR_CLI_SUP_FEAT_SZ; i++) {
feat[i] &= (BLE_GATT_CHR_CLI_SUP_FEAT_MASK >> (8 * i));
}

ble_hs_lock();
conn = ble_hs_conn_find(conn_handle);
if (conn == NULL) {
rc = BLE_ATT_ERR_UNLIKELY;
goto done;
}
if (om->om_len == 0) {
/* Nothing to do */
goto done;
} else if (os_mbuf_len(om) > BLE_ATT_ATTR_MAX_LEN) {
rc = BLE_ATT_ERR_INSUFFICIENT_RES;
goto done;
}

while(om) {
for (i = 0; i < om->om_len; i++) {
/**
* Disabling already enabled features is not permitted
* (Vol. 3, Part F, 3.3.3)
* If value of saved octet, as uint8_t, is greatet than requested
* it means more bits are set.
*/
if (conn->bhc_gatt_svr.peer_cl_sup_feat[feat_idx] >
om->om_data[i]) {
rc = BLE_ATT_ERR_VALUE_NOT_ALLOWED;
goto done;
}

/* All RFU bits should be unset */
if (feat_idx == 0) {
om->om_data[i] &= BLE_GATT_CHR_CLI_SUP_FEAT_MASK;
}

conn->bhc_gatt_svr.peer_cl_sup_feat[feat_idx] |= om->om_data[i];

feat_idx++;
/**
* Disabling already enabled features is not permitted
* (Vol. 3, Part F, 3.3.3)
*/
for (i = 0; i < BLE_GATT_CHR_CLI_SUP_FEAT_SZ; i++) {
if ((conn->bhc_gatt_svr.peer_cl_sup_feat[i] & feat[i]) !=
conn->bhc_gatt_svr.peer_cl_sup_feat[i]) {
rc = BLE_ATT_ERR_VALUE_NOT_ALLOWED;
goto done;
}
om = SLIST_NEXT(om, om_next);
}

memcpy(conn->bhc_gatt_svr.peer_cl_sup_feat, feat, BLE_GATT_CHR_CLI_SUP_FEAT_SZ);

done:
ble_hs_unlock();
return rc;
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