CVE-2022-49474 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: fix dangling sco_conn and use-after-free in sco_sock_timeout
Connecting the same socket twice consecutively in sco_sock_connect() could lead to a race condition where two sco_conn objects are created but only one is associated with the socket. If the socket is closed before the SCO connection is established, the timer associated with the dangling sco_conn object won't be canceled. As the sock object is being freed, the use-after-free problem happens when the timer callback function sco_sock_timeout() accesses the socket. Here's the call trace:
dump_stack+0x107/0x163 ? refcount_inc+0x1c/ print_address_description.constprop.0+0x1c/0x47e ? refcount_inc+0x1c/0x7b kasan_report+0x13a/0x173 ? refcount_inc+0x1c/0x7b check_memory_region+0x132/0x139 refcount_inc+0x1c/0x7b sco_sock_timeout+0xb2/0x1ba process_one_work+0x739/0xbd1 ? cancel_delayed_work+0x13f/0x13f ? __raw_spin_lock_init+0xf0/0xf0 ? to_kthread+0x59/0x85 worker_thread+0x593/0x70e kthread+0x346/0x35a ? drain_workqueue+0x31a/0x31a ? kthread_bind+0x4b/0x4b ret_from_fork+0x1f/0x30
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Analysis
by VulDB Data Team • 06/28/2025
This vulnerability exists within the Linux kernel's Bluetooth subsystem, specifically affecting the SCO (Synchronous Connection-Oriented) socket implementation. The issue stems from a race condition that occurs during the sco_sock_connect() function execution, where consecutive connections to the same socket can result in the creation of multiple sco_conn objects while only one remains properly associated with the socket. This fundamental flaw creates a dangling reference scenario that persists even after the socket has been closed, leading to a critical use-after-free condition when the timer callback function attempts to access freed memory resources.
The technical implementation flaw manifests through improper resource management and synchronization mechanisms within the Bluetooth SCO socket handling code. When a socket undergoes two consecutive connection attempts, the kernel creates two distinct sco_conn objects in memory but fails to properly clean up the orphaned reference. The timer associated with this dangling sco_conn object remains active even after the socket structure has been deallocated, creating a scenario where the sco_sock_timeout() callback function executes against memory that has already been freed. This memory access violation occurs because the kernel's reference counting mechanism does not properly account for the race condition, allowing the timer callback to access socket structures that are no longer valid, thereby triggering a kernel memory corruption event.
The operational impact of this vulnerability extends beyond simple memory corruption, as it represents a potential attack vector for privilege escalation and system instability within Linux environments that utilize Bluetooth connectivity. The use-after-free condition can lead to arbitrary code execution, system crashes, or denial of service scenarios, particularly in embedded systems or devices where Bluetooth functionality is critical. The vulnerability affects systems running Linux kernel versions that include the affected Bluetooth SCO socket implementation, making it relevant across various device types including smartphones, tablets, IoT devices, and server systems that support Bluetooth connectivity. The race condition exploitation requires specific timing and conditions but can be reliably triggered through controlled socket connection sequences.
Mitigation strategies for this vulnerability involve implementing proper synchronization mechanisms and resource cleanup procedures within the Bluetooth subsystem. Kernel developers should ensure that all timer callbacks are properly canceled before socket structures are freed, and that reference counting mechanisms account for all possible race conditions. The fix typically requires modifications to the sco_sock_connect() function to prevent the creation of multiple sco_conn objects when connections are attempted consecutively, along with proper cleanup of timer references in the socket destruction path. Organizations should apply the relevant kernel security patches immediately, particularly those addressing the Bluetooth SCO socket implementation, and implement monitoring for suspicious Bluetooth connection patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-416, representing an improper cleanup of memory resources, and could be categorized under ATT&CK technique T1059 for execution through kernel-level code injection, making it a critical security concern for enterprise environments.