CVE-2026-43023 — linux / linux_kernel
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: SCO: fix race conditions in sco_sock_connect()
sco_sock_connect() checks sk_state and sk_type without holding the socket lock. Two concurrent connect() syscalls on the same socket can both pass the check and enter sco_connect(), leading to use-after-free.
The buggy scenario involves three participants and was confirmed with additional logging instrumentation:
Thread A (connect): HCI disconnect: Thread B (connect):
sco_sock_connect(sk) sco_sock_connect(sk) sk_state==BT_OPEN sk_state==BT_OPEN (pass, no lock) (pass, no lock) sco_connect(sk): sco_connect(sk): hci_dev_lock hci_dev_lock hci_connect_sco <- blocked -> hcon1 sco_conn_add->conn1 lock_sock(sk) sco_chan_add: conn1->sk = sk sk->conn = conn1 sk_state=BT_CONNECT release_sock hci_dev_unlock hci_dev_lock sco_conn_del: lock_sock(sk) sco_chan_del: sk->conn=NULL conn1->sk=NULL sk_state= BT_CLOSED SOCK_ZAPPED release_sock hci_dev_unlock (unblocked) hci_connect_sco -> hcon2 sco_conn_add -> conn2 lock_sock(sk) sco_chan_add: sk->conn=conn2 sk_state= BT_CONNECT // zombie sk! release_sock hci_dev_unlock
Thread B revives a BT_CLOSED + SOCK_ZAPPED socket back to BT_CONNECT. Subsequent cleanup triggers double sock_put() and use-after-free. Meanwhile conn1 is leaked as it was orphaned when sco_conn_del() cleared the association.
Fix this by:
- Moving lock_sock() before the sk_state/sk_type checks in sco_sock_connect() to serialize concurrent connect attempts
- Fixing the sk_type != SOCK_SEQPACKET check to actually return the error instead of just assigning it
- Adding a state re-check in sco_connect() after lock_sock() to catch state changes during the window between the locks
- Adding sco_pi(sk)->conn check in sco_chan_add() to prevent double-attach of a socket to multiple connections
- Adding hci_conn_drop() on sco_chan_add failure to prevent HCI connection leaks
| Software | From | Fixed in |
|---|---|---|
| linux / linux_kernel | 6.1.109 | 6.1.168 |
| linux / linux_kernel | 6.3.1 | 6.6.134 |
| linux / linux_kernel | 6.7 | 6.12.81 |
| linux / linux_kernel | 6.13 | 6.18.22 |
| linux / linux_kernel | 6.19 | 6.19.12 |
| linux / linux_kernel | 6.3 | 6.3.x |
| linux / linux_kernel | 6.3-rc7 | 6.3-rc7.x |
| linux / linux_kernel | 7.0-rc1 | 7.0-rc1.x |
| linux / linux_kernel | 7.0-rc2 | 7.0-rc2.x |
| linux / linux_kernel | 7.0-rc3 | 7.0-rc3.x |
| linux / linux_kernel | 7.0-rc4 | 7.0-rc4.x |
| linux / linux_kernel | 7.0-rc5 | 7.0-rc5.x |
| linux / linux_kernel | 7.0-rc6 | 7.0-rc6.x |
- https://git.kernel.org/stable/c/7e296ffdab5bdab718dff7c14288fdcb9154fa27
- https://git.kernel.org/stable/c/8a5b0135d4a5d9683203a3d9a12a711ccec5936b
- https://git.kernel.org/stable/c/98c8d3bfdaa657d8f472dbbebd7ea8cd816d8a8d
- https://git.kernel.org/stable/c/adb90cd0f9f7a8d438fcb93354040fbafc5ae2a0
- https://git.kernel.org/stable/c/d002bd11024bd231bcb606877e33951ffb7bed14
- https://git.kernel.org/stable/c/dabf22269242e2f2bf44c43fcdc2fa763df7f9cc
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