CVE-2024-49851: 
Linux Kernel vulnerability analysis and mitigation

CVE-2024-49851 is a vulnerability in the Linux kernel's TPM (Trusted Platform Module) device driver that was discovered and disclosed on October 21, 2024. The issue affects the TPM space cleanup mechanism where tpmdevtransmit prepares the TPM space before attempting command transmission, but fails to perform proper cleanup if the command fails. This vulnerability impacts multiple versions of the Linux kernel, from version 4.12 through 6.11.2 (NVD).

The vulnerability stems from an incomplete cleanup process in the TPM device driver. When tpmdevtransmit prepares the TPM space before command transmission, no rollback of this preparation is performed if the command fails. This can result in transient handles being leaked if the device is subsequently closed without performing any further commands. The issue has been assigned a CVSS v3.1 base score of 5.5 (Medium) with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H. The vulnerability is classified as CWE-459 (Incomplete Cleanup) (NVD).

The primary impact of this vulnerability is the potential leakage of transient handles in the TPM device driver. This occurs when a command fails and the device is subsequently closed without performing additional commands. The vulnerability affects system availability but does not impact confidentiality or integrity, as indicated by the CVSS metrics (NVD).

The vulnerability has been fixed in the Linux kernel through a patch that implements proper cleanup of TPM space after command failure. The fix adds a call to tpm2flushspace when a command fails, ensuring proper cleanup of transient handles. The patch has been backported to multiple kernel versions and is available in various distribution updates (Kernel Patch).