Bug 2422840 (CVE-2025-68305)

Summary: CVE-2025-68305 kernel: Bluetooth: hci_sock: Prevent race in socket write iter and sock bind
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A use-after-free vulnerability was found in the Linux kernel's Bluetooth HCI socket implementation. A race condition between socket bind and write operations allows mgmt_pending to free a command structure while write_iter is still attempting to send it, resulting in use-after-free when the freed memory is accessed.
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Description OSIDB Bzimport 2025-12-16 16:05:39 UTC 
In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: hci_sock: Prevent race in socket write iter and sock bind

There is a potential race condition between sock bind and socket write
iter. bind may free the same cmd via mgmt_pending before write iter sends
the cmd, just as syzbot reported in UAF[1].

Here we use hci_dev_lock to synchronize the two, thereby avoiding the
UAF mentioned in [1].

[1]
syzbot reported:
BUG: KASAN: slab-use-after-free in mgmt_pending_remove+0x3b/0x210 net/bluetooth/mgmt_util.c:316
Read of size 8 at addr ffff888077164818 by task syz.0.17/5989
Call Trace:
 mgmt_pending_remove+0x3b/0x210 net/bluetooth/mgmt_util.c:316
 set_link_security+0x5c2/0x710 net/bluetooth/mgmt.c:1918
 hci_mgmt_cmd+0x9c9/0xef0 net/bluetooth/hci_sock.c:1719
 hci_sock_sendmsg+0x6ca/0xef0 net/bluetooth/hci_sock.c:1839
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:742
 sock_write_iter+0x279/0x360 net/socket.c:1195

Allocated by task 5989:
 mgmt_pending_add+0x35/0x140 net/bluetooth/mgmt_util.c:296
 set_link_security+0x557/0x710 net/bluetooth/mgmt.c:1910
 hci_mgmt_cmd+0x9c9/0xef0 net/bluetooth/hci_sock.c:1719
 hci_sock_sendmsg+0x6ca/0xef0 net/bluetooth/hci_sock.c:1839
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:742
 sock_write_iter+0x279/0x360 net/socket.c:1195

Freed by task 5991:
 mgmt_pending_free net/bluetooth/mgmt_util.c:311 [inline]
 mgmt_pending_foreach+0x30d/0x380 net/bluetooth/mgmt_util.c:257
 mgmt_index_removed+0x112/0x2f0 net/bluetooth/mgmt.c:9477
 hci_sock_bind+0xbe9/0x1000 net/bluetooth/hci_sock.c:1314
Comment 1 Alexander B 2025-12-16 17:10:07 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025121644-CVE-2025-68305-e40b@gregkh/T
Comment 4 errata-xmlrpc 2026-01-26 14:21:05 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:1143 https://access.redhat.com/errata/RHSA-2026:1143
Comment 5 errata-xmlrpc 2026-02-02 09:50:48 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:1690 https://access.redhat.com/errata/RHSA-2026:1690