From: Ruihan Li <lrh2000@xxxxxxxxxx> The hci_conn_unlink function is being called by hci_conn_del, which means it should not call hci_conn_del with the input parameter conn again. If it does, conn may have already been released when hci_conn_unlink returns, leading to potential UAF and double-free issues. This patch resolves the problem by modifying hci_conn_unlink to release only conn's child links when necessary, but never release conn itself. Reported-by: syzbot+690b90b14f14f43f4688@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://lore.kernel.org/linux-bluetooth/000000000000484a8205faafe216@xxxxxxxxxx/ Fixes: 06149746e720 ("Bluetooth: hci_conn: Add support for linking multiple hcon") Signed-off-by: Ruihan Li <lrh2000@xxxxxxxxxx> Reported-by: syzbot+690b90b14f14f43f4688@xxxxxxxxxxxxxxxxxxxxxxxxx Reported-by: Luiz Augusto von Dentz <luiz.dentz@xxxxxxxxx> Reported-by: syzbot+8bb72f86fc823817bc5d@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx> --- net/bluetooth/hci_conn.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c index 640b951bf40a..70e1655a9df6 100644 --- a/net/bluetooth/hci_conn.c +++ b/net/bluetooth/hci_conn.c @@ -1083,8 +1083,18 @@ static void hci_conn_unlink(struct hci_conn *conn) if (!conn->parent) { struct hci_link *link, *t; - list_for_each_entry_safe(link, t, &conn->link_list, list) - hci_conn_unlink(link->conn); + list_for_each_entry_safe(link, t, &conn->link_list, list) { + struct hci_conn *child = link->conn; + + hci_conn_unlink(child); + + /* 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. + */ + if (child->handle == HCI_CONN_HANDLE_UNSET) + hci_conn_del(child); + } return; } @@ -1100,13 +1110,6 @@ static void hci_conn_unlink(struct hci_conn *conn) kfree(conn->link); conn->link = NULL; - - /* 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. - */ - if (conn->handle == HCI_CONN_HANDLE_UNSET) - hci_conn_del(conn); } int hci_conn_del(struct hci_conn *conn) -- 2.40.0
