CVE-2023-53751

Vulnerability

Description

CVE-2023-53751 is a use-after-free vulnerability in the Linux kernel's CIFS (Common Internet File System) client. The root cause is that the TCP_Server_Info::hostname field can be updated multiple times during reconnection, but accesses to this field outside the reconnect path are not properly protected. This lack of synchronization can lead to a use-after-free condition when a concurrent access occurs while the hostname is being freed or reallocated [1][2].

Exploitation

An attacker would need to be able to trigger a CIFS reconnection event, which typically requires network-level access to disrupt the connection between the client and the SMB server. No special privileges on the client are necessary beyond the ability to mount a CIFS share. The race condition occurs when the hostname is accessed (e.g., for logging or connection management) while a reconnect is in progress, potentially allowing an attacker to exploit the freed memory [1][2].

Impact

Successful exploitation could allow an attacker to a use-after-free, which may lead to memory corruption, denial of service (system crash), or potentially arbitrary code execution in kernel context. The exact impact depends on the memory layout and the attacker's ability to control the freed memory [1][2].

Mitigation

The fix has been applied to the Linux kernel stable tree. Users should update to a kernel version containing the commit that adds proper locking around hostname accesses. No workaround is available other than applying the patch [1][2].