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.
Fixes: 06149746e720 ("Bluetooth: hci_conn: Add support for linking multiple hcon")
Signed-off-by: Ruihan Li <lrh2000@xxxxxxxxxx>
---
Changes since v1:
* CI complains that there are some merge conflicts. This is because
void hci_conn_del(struct hci_conn *conn)
this completely unrelated line makes the patch dependent on another fix:
https://lore.kernel.org/linux-bluetooth/20230430171847.156825-1-lrh2000@xxxxxxxxxx/
But actually, deleting that line makes the two patches independent of
each other, and everything still works.
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 85c34c837..5f388202f 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;
}
@@ -1100,12 +1110,5 @@ 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);
}
--
2.40.0
