In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_event: fix LE list UAF on reset
hci_cc_reset() clears the LE accept and resolving lists without taking
hdev->lock. Other command-complete handlers serialize updates to these
lists with that lock, and the debugfs readers hold it while walking them.
This permits the reset completion and a debugfs read to interleave as
follows:
hci_rx_work debugfs reader
———– ————–
lock hdev->lock
fetch current entry
list_del(entry)
kfree(entry)
read entry fields
The reader then dereferences a freed list entry and may follow its stale
next pointer.
KASAN reported:
BUG: KASAN: slab-use-after-free in white_list_show+0x15f/0x180
Read of size 1 at addr ffff8881015dab16 by task poc/95
Call Trace:
white_list_show+0x15f/0x180
seq_read_iter+0x3ff/0x1190
seq_read+0x267/0x3d0
vfs_read+0x177/0xa20
ksys_read+0xf7/0x1c0
Allocated by task 91:
hci_bdaddr_list_add+0x1a6/0x3a0
hci_cc_le_add_to_accept_list+0xab/0x140
hci_cmd_complete_evt+0x26c/0x9a0
hci_event_packet+0x454/0xb20
hci_rx_work+0x293/0x730
Freed by task 90:
kfree+0x131/0x3c0
hci_bdaddr_list_clear+0xd8/0x160
hci_cc_reset+0x28a/0x370
hci_cmd_complete_evt+0x26c/0x9a0
hci_event_packet+0x454/0xb20
hci_rx_work+0x293/0x730
Take hdev->lock around both list clears. This matches the existing
mutation and traversal locking convention.
