In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_sync: Serialize local codec list cleanup
hci_dev_close_sync() clears hdev->local_codecs after releasing hdev->lock. Codec list additions and both traversals in sco_sock_getsockopt() use that lock, but the close path does not. A close and BT_CODEC query can therefore interleave as follows:
hci_dev_close_sync() sco_sock_getsockopt() hci_dev_lock() fetch codec entry hci_codec_list_clear() kfree(entry) read entry->id
The reader then accesses an entry which the close path has freed. KASAN
BUG: KASAN: slab-use-after-free in sco_sock_getsockopt+0xfa0/0xfe0 Read of size 1 at addr ffff8881001c3450 Call Trace: sco_sock_getsockopt+0xfa0/0xfe0 do_sock_getsockopt+0x537/0x7b0 __sys_getsockopt+0xf2/0x170 Allocated by task 92: hci_codec_list_add.isra.0+0x2c/0x440 hci_read_codec_capabilities+0x224/0x590 hci_read_supported_codecs+0x2c2/0x640 Freed by task 92: kfree+0x131/0x3c0 hci_codec_list_clear+0xd8/0x160 hci_dev_close_sync+0x92a/0xfa0
Take hdev->lock around the clear operation at its existing point in the close path. This makes the clear wait for active readers and prevents a new traversal until the list is empty without changing teardown ordering.
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