CVE-2026-93247

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

Bluetooth: mgmt: fix 'hdev->discovery.uuids' NULL dereference

'uuid_count' member of struct 'discovery_state' is assigned and read

without any locks, so there is a chance of situation when

uuid_count != 0, but uuids is NULL and there will be NULL pointer

dereference.

Possible race:

'hci_update_passive_scan_sync'

'hci_discovery_filter_clear'

hdev->discovery.uuid_count = 0;

<----------------------preempted----------------------------->

'start_service_discovery'

// Set uuid_count to value != 0

hdev->discovery.uuid_count = uuid_count;

hdev->discovery.uuids = kmemdup(...);

<----------------------preempted----------------------------->

spin_lock(&hdev->discovery.lock);

kfree(hdev->discovery.uuids);

hdev->discovery.uuids = NULL;

spin_unlock(&hdev->discovery.lock);

Now uuids == NULL and uuid_count != 0.

So 'mgmt_device_found' -> 'is_filter_match' -> 'eir_has_uuids' receives

non consistent discovery state, where NULL dereference of uuids happens.

To fix it let's add discovery.lock around every read/write of uuid_count,

uuids pair of struct members. It is also important to assign uuid_count

value only after success kmemdup() allocation in

start_service_discovery(), otherwise uuids is NULL, because kmemdup failed,

but uuid_count is already assigned to non zero value.

The following panic happens:

[ ] ------------[ cut here ]------------

[ ] Unable to handle kernel NULL pointer dereference at virtual

address 0000000000000000

[ ] Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP

[ ] CPU: 0 PID: 15056 Comm: kworker/u9:2

[ ] Workqueue: hci0 hci_rx_work

[ ] pstate: 10400009 (nzcV daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)

[ ] pc : eir_has_uuids+0x2d8/0x590

[ ] lr : is_filter_match+0x258/0x320

...

[ ] Call trace:

[ ] eir_has_uuids+0x2d8/0x590

[ ] is_filter_match+0x258/0x320

[ ] mgmt_device_found+0x5b0/0xafc

[ ] process_adv_report.part.0+0x8c8/0xf14

[ ] hci_le_adv_report_evt+0x338/0x3f0

[ ] hci_le_meta_evt+0x1f0/0x4c8

[ ] hci_event_packet+0x440/0xc9c

[ ] hci_rx_work+0x44c/0xaf8

[ ] process_one_work+0x54c/0x103c

[ ] worker_thread+0x6c4/0x10c4

[ ] kthread+0x274/0x2ec

[ ] ret_from_fork+0x10/0x20

[ ] Code: 14000004 91004021 eb14003f 54000180 (f9400024)

[ ] ---[ end trace 0000000000000000 ]---