Executive brief
A vulnerability in the Linux kernel's SMB client could allow a local user to cause a system deadlock. This component is responsible for connecting to network file shares (SMB/CIFS). If exploited, the system may become unresponsive, leading to a denial of service that disrupts operations and requires a reboot.
Technical details
A deadlock vulnerability exists in the smb2_find_smb_tcon() function within the Linux kernel's SMB client implementation. The issue is caused by improper lock management where cifs_tcp_ses_lock is held while calling cifs_put_smb_ses(), which can lead to a circular dependency and subsequent kernel deadlock. An attacker with local access could trigger this condition to cause a denial of service (system hang). The fix involves reordering the operations to unlock cifs_tcp_ses_lock before invoking cifs_put_smb_ses(). Patches have been released across multiple stable kernel branches including 5.10, 5.15, 6.1, 6.6, and 6.9.
Affected products
- Linux Linux Kernel up to 5.10.221, 5.11 to 5.15.162, 5.16 to 6.1.94, 6.2 to 6.6.34, 6.7 to 6.9.5
Timeline
- 2024-06-25: disclosed
- 2024-06-25: advisory
- 2024-06-07: patched: Initial patch committed to stable tree.
References
- https://git.kernel.org/stable/c/02c418774f76a0a36a6195c9dbf8971eb4130a15
- https://git.kernel.org/stable/c/21f5dd36e655d25a7b45b61c1e537198b671f720
- https://git.kernel.org/stable/c/225de871ddf994f69a57f035709cad9c0ab8615a
- https://git.kernel.org/stable/c/8d0f5f1ccf675454a833a573c53830a49b7d1a47
- https://git.kernel.org/stable/c/b055752675cd1d1db4ac9c2750db3dc3e89ea261
- https://git.kernel.org/stable/c/b09b556e48968317887a11243a5331a7bc00ece5
- https://cert-portal.siemens.com/productcert/html/ssa-265688.html