Re: [PATCH] Bluetooth: verify AMP hci_chan before amp_destroy

[Marcel Holtmann]

Hi Archie,

> hci_chan can be created in 2 places: hci_loglink_complete_evt() if
> it is an AMP hci_chan, or l2cap_conn_add() otherwise. In theory,
> Only AMP hci_chan should be removed by a call to
> hci_disconn_loglink_complete_evt(). However, the controller might mess
> up, call that function, and destroy an hci_chan which is not initiated
> by hci_loglink_complete_evt().
> 
> This patch adds a verification that the destroyed hci_chan must have
> been init'd by hci_loglink_complete_evt().
> 
> Example crash call trace:
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0xe3/0x144 lib/dump_stack.c:118
> print_address_description+0x67/0x22a mm/kasan/report.c:256
> kasan_report_error mm/kasan/report.c:354 [inline]
> kasan_report mm/kasan/report.c:412 [inline]
> kasan_report+0x251/0x28f mm/kasan/report.c:396
> hci_send_acl+0x3b/0x56e net/bluetooth/hci_core.c:4072
> l2cap_send_cmd+0x5af/0x5c2 net/bluetooth/l2cap_core.c:877
> l2cap_send_move_chan_cfm_icid+0x8e/0xb1 net/bluetooth/l2cap_core.c:4661
> l2cap_move_fail net/bluetooth/l2cap_core.c:5146 [inline]
> l2cap_move_channel_rsp net/bluetooth/l2cap_core.c:5185 [inline]
> l2cap_bredr_sig_cmd net/bluetooth/l2cap_core.c:5464 [inline]
> l2cap_sig_channel net/bluetooth/l2cap_core.c:5799 [inline]
> l2cap_recv_frame+0x1d12/0x51aa net/bluetooth/l2cap_core.c:7023
> l2cap_recv_acldata+0x2ea/0x693 net/bluetooth/l2cap_core.c:7596
> hci_acldata_packet net/bluetooth/hci_core.c:4606 [inline]
> hci_rx_work+0x2bd/0x45e net/bluetooth/hci_core.c:4796
> process_one_work+0x6f8/0xb50 kernel/workqueue.c:2175
> worker_thread+0x4fc/0x670 kernel/workqueue.c:2321
> kthread+0x2f0/0x304 kernel/kthread.c:253
> ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415
> 
> Allocated by task 38:
> set_track mm/kasan/kasan.c:460 [inline]
> kasan_kmalloc+0x8d/0x9a mm/kasan/kasan.c:553
> kmem_cache_alloc_trace+0x102/0x129 mm/slub.c:2787
> kmalloc include/linux/slab.h:515 [inline]
> kzalloc include/linux/slab.h:709 [inline]
> hci_chan_create+0x86/0x26d net/bluetooth/hci_conn.c:1674
> l2cap_conn_add.part.0+0x1c/0x814 net/bluetooth/l2cap_core.c:7062
> l2cap_conn_add net/bluetooth/l2cap_core.c:7059 [inline]
> l2cap_connect_cfm+0x134/0x852 net/bluetooth/l2cap_core.c:7381
> hci_connect_cfm+0x9d/0x122 include/net/bluetooth/hci_core.h:1404
> hci_remote_ext_features_evt net/bluetooth/hci_event.c:4161 [inline]
> hci_event_packet+0x463f/0x72fa net/bluetooth/hci_event.c:5981
> hci_rx_work+0x197/0x45e net/bluetooth/hci_core.c:4791
> process_one_work+0x6f8/0xb50 kernel/workqueue.c:2175
> worker_thread+0x4fc/0x670 kernel/workqueue.c:2321
> kthread+0x2f0/0x304 kernel/kthread.c:253
> ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415
> 
> Freed by task 1732:
> set_track mm/kasan/kasan.c:460 [inline]
> __kasan_slab_free mm/kasan/kasan.c:521 [inline]
> __kasan_slab_free+0x106/0x128 mm/kasan/kasan.c:493
> slab_free_hook mm/slub.c:1409 [inline]
> slab_free_freelist_hook+0xaa/0xf6 mm/slub.c:1436
> slab_free mm/slub.c:3009 [inline]
> kfree+0x182/0x21e mm/slub.c:3972
> hci_disconn_loglink_complete_evt net/bluetooth/hci_event.c:4891 [inline]
> hci_event_packet+0x6a1c/0x72fa net/bluetooth/hci_event.c:6050
> hci_rx_work+0x197/0x45e net/bluetooth/hci_core.c:4791
> process_one_work+0x6f8/0xb50 kernel/workqueue.c:2175
> worker_thread+0x4fc/0x670 kernel/workqueue.c:2321
> kthread+0x2f0/0x304 kernel/kthread.c:253
> ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415
> 
> The buggy address belongs to the object at ffff8881d7af9180
> which belongs to the cache kmalloc-128 of size 128
> The buggy address is located 24 bytes inside of
> 128-byte region [ffff8881d7af9180, ffff8881d7af9200)
> The buggy address belongs to the page:
> page:ffffea00075ebe40 count:1 mapcount:0 mapping:ffff8881da403200 index:0x0
> flags: 0x8000000000000200(slab)
> raw: 8000000000000200 dead000000000100 dead000000000200 ffff8881da403200
> raw: 0000000000000000 0000000080150015 00000001ffffffff 0000000000000000
> page dumped because: kasan: bad access detected
> 
> Memory state around the buggy address:
> ffff8881d7af9080: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
> ffff8881d7af9100: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>> ffff8881d7af9180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                            ^
> ffff8881d7af9200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff8881d7af9280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> 
> Signed-off-by: Archie Pusaka <apusaka@xxxxxxxxxxxx>
> Reported-by: syzbot+98228e7407314d2d4ba2@xxxxxxxxxxxxxxxxxxxxxxxxx
> Reviewed-by: Alain Michaud <alainm@xxxxxxxxxxxx>
> Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>
> ---
> 
> include/net/bluetooth/hci_core.h | 1 +
> net/bluetooth/hci_event.c        | 3 ++-
> 2 files changed, 3 insertions(+), 1 deletion(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel