CVE-2026-98737

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.