Bluetooth: hci_core: Serialize fragmented ISO packet queueing

Overview

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

Bluetooth: hci_core: Serialize fragmented ISO packet queueing

The fragmented path in hci_queue_iso() calls __skb_queue_tail() without holding conn->data_q.lock. The socket lock serializes senders, but the transmit worker can concurrently remove packets from this queue using skb_dequeue().

After an insertion saves the old tail pointer, hci_sched_iso() can dequeue that packet and pass it to the driver. The driver can free the packet before the insertion resumes and writes to the old tail's next pointer, causing a use-after-free. Concurrent updates can also corrupt the queue.

KASAN reported:

BUG: KASAN: slab-use-after-free in hci_send_iso+0xc7d/0xe10 Call Trace: hci_send_iso+0xc7d/0xe10 iso_sock_sendmsg+0x710/0x900 __sys_sendto+0x34a/0x3a0

Allocated by task 86: __alloc_skb+0xdd/0x820 alloc_skb_with_frags+0x7e/0x770 sock_alloc_send_pskb+0x67a/0x820 bt_skb_sendmsg.constprop.0+0xc0/0x6c0 iso_sock_sendmsg+0x44e/0x900

Freed by task 90: kmem_cache_free+0xcb/0x3d0 vhci_read+0x33f/0x4d0 vfs_read+0x177/0xa20

Hold the queue lock across the entire fragment batch, as hci_queue_acl() does, to serialize insertion against dequeue while preserving fragment ordering.

Affected

• Linux >= 26afbd826ee326e63a334c37fd45e82e50a615ec < d6d709981208567868c5c01ebd1bec5e5e7fdab0
• Linux >= 26afbd826ee326e63a334c37fd45e82e50a615ec < 708cdd203d0bbcf9255fffb2e4c308d5b28851a7
• Linux >= 26afbd826ee326e63a334c37fd45e82e50a615ec < a7161730a3ab3f0a3896000db7ab0284683936e6
• Linux >= 26afbd826ee326e63a334c37fd45e82e50a615ec < 1a572db43c057566771b485598ad2e66cb390821
• Linux 6.0

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.