CVE-2024-56653

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: btmtk: avoid UAF in btmtk_process_coredump

hci_devcd_append may lead to the release of the skb, so it cannot be

accessed once it is called.

==================================================================

BUG: KASAN: slab-use-after-free in btmtk_process_coredump+0x2a7/0x2d0 [btmtk]

Read of size 4 at addr ffff888033cfabb0 by task kworker/0:3/82

CPU: 0 PID: 82 Comm: kworker/0:3 Tainted: G U 6.6.40-lockdep-03464-g1d8b4eb3060e #1 b0b3c1cc0c842735643fb411799d97921d1f688c

Hardware name: Google Yaviks_Ufs/Yaviks_Ufs, BIOS Google_Yaviks_Ufs.15217.552.0 05/07/2024

Workqueue: events btusb_rx_work [btusb]

Call Trace:

<TASK>

dump_stack_lvl+0xfd/0x150

print_report+0x131/0x780

kasan_report+0x177/0x1c0

btmtk_process_coredump+0x2a7/0x2d0 [btmtk 03edd567dd71a65958807c95a65db31d433e1d01]

btusb_recv_acl_mtk+0x11c/0x1a0 [btusb 675430d1e87c4f24d0c1f80efe600757a0f32bec]

btusb_rx_work+0x9e/0xe0 [btusb 675430d1e87c4f24d0c1f80efe600757a0f32bec]

worker_thread+0xe44/0x2cc0

kthread+0x2ff/0x3a0

ret_from_fork+0x51/0x80

ret_from_fork_asm+0x1b/0x30

</TASK>

Allocated by task 82:

stack_trace_save+0xdc/0x190

kasan_set_track+0x4e/0x80

__kasan_slab_alloc+0x4e/0x60

kmem_cache_alloc+0x19f/0x360

skb_clone+0x132/0xf70

btusb_recv_acl_mtk+0x104/0x1a0 [btusb]

btusb_rx_work+0x9e/0xe0 [btusb]

worker_thread+0xe44/0x2cc0

kthread+0x2ff/0x3a0

ret_from_fork+0x51/0x80

ret_from_fork_asm+0x1b/0x30

Freed by task 1733:

stack_trace_save+0xdc/0x190

kasan_set_track+0x4e/0x80

kasan_save_free_info+0x28/0xb0

____kasan_slab_free+0xfd/0x170

kmem_cache_free+0x183/0x3f0

hci_devcd_rx+0x91a/0x2060 [bluetooth]

worker_thread+0xe44/0x2cc0

kthread+0x2ff/0x3a0

ret_from_fork+0x51/0x80

ret_from_fork_asm+0x1b/0x30

The buggy address belongs to the object at ffff888033cfab40

which belongs to the cache skbuff_head_cache of size 232

The buggy address is located 112 bytes inside of

freed 232-byte region [ffff888033cfab40, ffff888033cfac28)

The buggy address belongs to the physical page:

page:00000000a174ba93 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33cfa

head:00000000a174ba93 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0

anon flags: 0x4000000000000840(slab|head|zone=1)

page_type: 0xffffffff()

raw: 4000000000000840 ffff888100848a00 0000000000000000 0000000000000001

raw: 0000000000000000 0000000080190019 00000001ffffffff 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff888033cfaa80: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc

ffff888033cfab00: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb

>ffff888033cfab80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^

ffff888033cfac00: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc

ffff888033cfac80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

==================================================================

Check if we need to call hci_devcd_complete before calling

hci_devcd_append. That requires that we check data->cd_info.cnt >=

MTK_COREDUMP_NUM instead of data->cd_info.cnt > MTK_COREDUMP_NUM, as we

increment data->cd_info.cnt only once the call to hci_devcd_append

succeeds.