Bug 2555088 (CVE-2026-98737)

Summary:	CVE-2026-98737 kernel: kernel: Denial of service via Bluetooth inquiry cache use-after-free
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	rhel-process-autobot, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's Bluetooth subsystem. This flaw allows a local user to cause a Denial of Service (DoS) or potentially escalate privileges due to a use-after-free condition. The issue arises from a race condition where synchronous command routines access inquiry cache entries without proper locking, allowing a concurrent cache flush request to free memory that is still actively in use.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-10-18 15:53:44 UTC

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

Bluetooth: hci_sync: Fix inquiry cache use-after-free

The sync command worker holds hdev->req_lock, but inquiry-cache updates
and flushes use hdev->lock. Both hci_acl_create_conn_sync() and
hci_stop_discovery_sync() look up entries and read their fields without
taking hdev->lock.

After either lookup returns, a concurrent HCIINQUIRY ioctl can acquire
hdev->lock and flush the cache, freeing the entry. The worker then reads
the freed entry while preparing a create-connection or remote-name-cancel
command. The list traversal also races with cache updates and removal.

KASAN reported these accesses:

  BUG: KASAN: slab-use-after-free in hci_acl_create_conn_sync+0x5f1/0x650
  Workqueue: hci0 hci_cmd_sync_work
  Call Trace:
   hci_acl_create_conn_sync+0x5f1/0x650
   hci_cmd_sync_work+0x13c/0x290

  Allocated by task 90:
   hci_inquiry_cache_update+0x3e6/0x7d0
   hci_inquiry_result_evt+0x3cb/0x560

  Freed by task 93:
   hci_inquiry_cache_flush+0x111/0x2b0
   hci_inquiry+0x2f2/0x780
   hci_sock_ioctl+0x269/0x5f0

  BUG: KASAN: slab-use-after-free in hci_stop_discovery_sync+0x3b1/0x3c0
  Workqueue: hci0 hci_cmd_sync_work
  Call Trace:
   hci_stop_discovery_sync+0x3b1/0x3c0
   hci_cmd_sync_work+0x173/0x300

  Allocated by task 86:
   hci_inquiry_cache_update+0x483/0x940
   hci_inquiry_result_evt+0x3cb/0x560

  Freed by task 91:
   hci_inquiry_cache_flush+0x13e/0x2f0
   hci_inquiry+0x2f2/0x780
   hci_sock_ioctl+0x269/0x5f0

Hold hdev->lock across each lookup and all reads from its result. Copy the
remote address before unlocking so discovery cancellation does not retain
a cache entry pointer. Release the lock before sending synchronous HCI
commands, since their completion handlers may need the same lock.