@@ -1327,7 +1327,7 @@ int hci_le_create_cis(struct hci_conn *conn);
struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst,
u8 role);
-int hci_conn_del(struct hci_conn *conn);
+void hci_conn_del(struct hci_conn *conn);
void hci_conn_hash_flush(struct hci_dev *hdev);
void hci_conn_check_pending(struct hci_dev *hdev);
@@ -1088,6 +1088,14 @@ static void hci_conn_unlink(struct hci_conn *conn)
hci_conn_unlink(child);
+ /* If hdev is down it means
+ * hci_dev_close_sync/hci_conn_hash_flush is in progress
+ * and links don't need to be cleanup as all connections
+ * would be cleanup.
+ */
+ if (!test_bit(HCI_UP, &hdev->flags))
+ continue;
+
/* Due to race, SCO connection might be not established
* yet at this point. Delete it now, otherwise it is
* possible for it to be stuck and can't be deleted.
@@ -1112,7 +1120,7 @@ static void hci_conn_unlink(struct hci_conn *conn)
conn->link = NULL;
}
-int hci_conn_del(struct hci_conn *conn)
+void hci_conn_del(struct hci_conn *conn)
{
struct hci_dev *hdev = conn->hdev;
@@ -1163,8 +1171,6 @@ int hci_conn_del(struct hci_conn *conn)
* rest of hci_conn_del.
*/
hci_conn_cleanup(conn);
-
- return 0;
}
struct hci_dev *hci_get_route(bdaddr_t *dst, bdaddr_t *src, uint8_t src_type)
@@ -2465,22 +2471,27 @@ void hci_conn_enter_active_mode(struct hci_conn *conn, __u8 force_active)
/* Drop all connection on the device */
void hci_conn_hash_flush(struct hci_dev *hdev)
{
- struct hci_conn_hash *h = &hdev->conn_hash;
- struct hci_conn *c, *n;
+ struct list_head *head = &hdev->conn_hash.list;
+ struct hci_conn *conn;
BT_DBG("hdev %s", hdev->name);
- list_for_each_entry_safe(c, n, &h->list, list) {
- c->state = BT_CLOSED;
-
- hci_disconn_cfm(c, HCI_ERROR_LOCAL_HOST_TERM);
+ /* We should not traverse the list here, because hci_conn_del
+ * can remove extra links, which may cause the list traversal
+ * to hit items that have already been released.
+ */
+ while ((conn = list_first_entry_or_null(head,
+ struct hci_conn,
+ list)) != NULL) {
+ conn->state = BT_CLOSED;
+ hci_disconn_cfm(conn, HCI_ERROR_LOCAL_HOST_TERM);
/* Unlink before deleting otherwise it is possible that
* hci_conn_del removes the link which may cause the list to
* contain items already freed.
*/
- hci_conn_unlink(c);
- hci_conn_del(c);
+ hci_conn_unlink(conn);
+ hci_conn_del(conn);
}
}
Commit 06149746e720 ("Bluetooth: hci_conn: Add support for linking multiple hcon") reintroduced a previously fixed bug [1] ("KASAN: slab-use-after-free Read in hci_conn_hash_flush"). This bug was originally fixed by commit 5dc7d23e167e ("Bluetooth: hci_conn: Fix possible UAF"). The hci_conn_unlink function was added to avoid invalidating the link traversal caused by successive hci_conn_del operations releasing extra connections. However, currently hci_conn_unlink itself also releases extra connections, resulted in the reintroduced bug. This patch follows a more robust solution for cleaning up all connections, by repeatedly removing the first connection until there are none left. This approach does not rely on the inner workings of hci_conn_del and ensures proper cleanup of all connections. Meanwhile, we need to make sure that hci_conn_del never fails. Indeed it doesn't, as it now always returns zero. To make this a bit clearer, this patch also changes its return type to void. Reported-by: syzbot+8bb72f86fc823817bc5d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-bluetooth/000000000000aa920505f60d25ad@google.com/ Fixes: 06149746e720 ("Bluetooth: hci_conn: Add support for linking multiple hcon") Signed-off-by: Ruihan Li <lrh2000@pku.edu.cn> Co-developed-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> --- include/net/bluetooth/hci_core.h | 2 +- net/bluetooth/hci_conn.c | 33 +++++++++++++++++++++----------- 2 files changed, 23 insertions(+), 12 deletions(-)