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 lets 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 ]—

Affected Software

References

• https://git.kernel.org/stable/c/18fda026a13c5abd6c1e0dfd3549f490b73378fb
• https://git.kernel.org/stable/c/59eecbe2f2f38d8f3e1104bd11da97f9a2c58998
• https://git.kernel.org/stable/c/bbd262d2d750b67b15a5e1008d3848309c87e7a7
• https://git.kernel.org/stable/c/c3f63610bceaa182e4683b23cc47baf36b5f1496
• https://git.kernel.org/stable/c/ee2135a14fb2a3e176149122764d293f0796b1eb
• https://git.kernel.org/stable/c/f02c01ccd12cb2b8a290077d4c90f29a6e109b16