From: Ruihan Li lrh2000@pku.edu.cn
commit ca1fd42e7dbfcb34890ffbf1f2f4b356776dab6f upstream.
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@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-bluetooth/000000000000484a8205faafe216@google.... Fixes: 06149746e720 ("Bluetooth: hci_conn: Add support for linking multiple hcon") Signed-off-by: Ruihan Li lrh2000@pku.edu.cn Signed-off-by: Luiz Augusto von Dentz luiz.von.dentz@intel.com Reported-by: syzbot+690b90b14f14f43f4688@syzkaller.appspotmail.com Reported-by: Luiz Augusto von Dentz luiz.dentz@gmail.com Reported-by: syzbot+8bb72f86fc823817bc5d@syzkaller.appspotmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/bluetooth/hci_conn.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-)
--- a/net/bluetooth/hci_conn.c +++ b/net/bluetooth/hci_conn.c @@ -1088,8 +1088,18 @@ static void hci_conn_unlink(struct hci_c 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; } @@ -1105,13 +1115,6 @@ static void hci_conn_unlink(struct hci_c
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)