From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
This fixes the following trace:
==================================================================
BUG: KASAN: slab-use-after-free in hci_conn_del+0xba/0x3a0
Write of size 8 at addr ffff88800208e9c8 by task iso-tester/31
CPU: 0 PID: 31 Comm: iso-tester Not tainted 6.3.0-rc2-g991aa4a69a47
#4716
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.1-2.fc36
04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x1d/0x70
print_report+0xce/0x610
? __virt_addr_valid+0xd4/0x150
? hci_conn_del+0xba/0x3a0
kasan_report+0xdd/0x110
? hci_conn_del+0xba/0x3a0
hci_conn_del+0xba/0x3a0
hci_conn_hash_flush+0xf2/0x120
hci_dev_close_sync+0x388/0x920
hci_unregister_dev+0x122/0x260
vhci_release+0x4f/0x90
__fput+0x102/0x430
task_work_run+0xf1/0x160
? __pfx_task_work_run+0x10/0x10
? mark_held_locks+0x24/0x90
exit_to_user_mode_prepare+0x170/0x180
syscall_exit_to_user_mode+0x19/0x50
do_syscall_64+0x4e/0x90
entry_SYSCALL_64_after_hwframe+0x70/0xda
Fixes: 0f00cd322d22 ("Bluetooth: Free potentially unfreed SCO connection")
Link: https://syzkaller.appspot.com/bug?extid=8bb72f86fc823817bc5d
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
---
net/bluetooth/hci_conn.c | 30 ++++++++++++++++++++++++------
1 file changed, 24 insertions(+), 6 deletions(-)
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index fe8d54f8f04f..5672b4924572 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1069,6 +1069,17 @@ struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst,
return conn;
}
+static bool hci_conn_unlink(struct hci_conn *conn)
+{
+ if (!conn->link)
+ return false;
+
+ conn->link->link = NULL;
+ conn->link = NULL;
+
+ return true;
+}
+
int hci_conn_del(struct hci_conn *conn)
{
struct hci_dev *hdev = conn->hdev;
@@ -1080,15 +1091,16 @@ int hci_conn_del(struct hci_conn *conn)
cancel_delayed_work_sync(&conn->idle_work);
if (conn->type == ACL_LINK) {
- struct hci_conn *sco = conn->link;
- if (sco) {
- sco->link = NULL;
+ struct hci_conn *link = conn->link;
+
+ if (link) {
+ hci_conn_unlink(conn);
/* 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 (sco->handle == HCI_CONN_HANDLE_UNSET)
- hci_conn_del(sco);
+ if (link->handle == HCI_CONN_HANDLE_UNSET)
+ hci_conn_del(link);
}
/* Unacked frames */
@@ -1104,7 +1116,7 @@ int hci_conn_del(struct hci_conn *conn)
struct hci_conn *acl = conn->link;
if (acl) {
- acl->link = NULL;
+ hci_conn_unlink(conn);
hci_conn_drop(acl);
}
@@ -2444,6 +2456,12 @@ void hci_conn_hash_flush(struct hci_dev *hdev)
c->state = BT_CLOSED;
hci_disconn_cfm(c, 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);
}
}
--
2.39.2
