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

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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.

Fixes: cf75ad8b41 ("Bluetooth: hci_sync: Convert MGMT_SET_POWERED")
Fixes: 45340097ce ("Bluetooth: hci_conn: Only do ACL connections sequentially")
Cc: stable@vger.kernel.org
Signed-off-by: Chengfeng Ye <nicoyip.dev@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
This commit is contained in:
Chengfeng Ye 2026-09-27 01:28:31 +08:00 committed by Luiz Augusto von Dentz
parent b1f24c1ab5
commit 8ed67535fd
1 changed files with 11 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
net/bluetooth/hci_sync.c
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@ -5770,6 +5770,7 @@ int hci_stop_discovery_sync(struct hci_dev *hdev)
{
struct discovery_state *d = &hdev->discovery;
struct inquiry_entry *e;
bdaddr_t addr;
int err;
bt_dev_dbg(hdev, "state %u", hdev->discovery.state);
@ -5805,15 +5806,21 @@ int hci_stop_discovery_sync(struct hci_dev *hdev)
return 0;
if (d->state == DISCOVERY_RESOLVING || d->state == DISCOVERY_STOPPING) {
hci_dev_lock(hdev);
e = hci_inquiry_cache_lookup_resolve(hdev, BDADDR_ANY,
NAME_PENDING);
if (!e)
if (!e) {
hci_dev_unlock(hdev);
return 0;
}
bacpy(&addr, &e->data.bdaddr);
hci_dev_unlock(hdev);
/* Ignore cancel errors since it should interfere with stopping
* of the discovery.
*/
hci_remote_name_cancel_sync(hdev, &e->data.bdaddr);
hci_remote_name_cancel_sync(hdev, &addr);
}
return 0;
@ -7242,6 +7249,7 @@ static int hci_acl_create_conn_sync(struct hci_dev *hdev, void *data)
bacpy(&cp.bdaddr, &conn->dst);
cp.pscan_rep_mode = 0x02;
hci_dev_lock(hdev);
ie = hci_inquiry_cache_lookup(hdev, &conn->dst);
if (ie) {
if (inquiry_entry_age(ie) <= INQUIRY_ENTRY_AGE_MAX) {
@ -7253,6 +7261,7 @@ static int hci_acl_create_conn_sync(struct hci_dev *hdev, void *data)
memcpy(conn->dev_class, ie->data.dev_class, 3);
}
hci_dev_unlock(hdev);
cp.pkt_type = cpu_to_le16(conn->pkt_type);
if (lmp_rswitch_capable(hdev) && !(hdev->link_mode & HCI_LM_MASTER))