CVE-2023-53597

In the Linux kernel, the following vulnerability has been resolved:

cifs: fix mid leak during reconnection after timeout threshold

When the number of responses with status of STATUS_IO_TIMEOUT exceeds a specified threshold (NUM_STATUS_IO_TIMEOUT), we reconnect the connection. But we do not return the mid, or the credits returned for the mid, or reduce the number of in-flight requests.

This bug could result in the server->in_flight count to go bad, and also cause a leak in the mids.

This change moves the check to a few lines below where the response is decrypted, even of the response is read from the transform header. This way, the code for returning the mids can be reused.

Also, the cifs_reconnect was reconnecting just the transport connection before. In case of multi-channel, this may not be what we want to do after several timeouts. Changed that to reconnect the session and the tree too.

Also renamed NUM_STATUS_IO_TIMEOUT to a more appropriate name MAX_STATUS_IO_TIMEOUT.

This vulnerability is rated as Moderate impact for Red Hat Enterprise Linux because exploiting the issue requires an established CIFS mount subjected to persistent network timeouts, confining the primary risk to local resource exhaustion. In default Red Hat installations, the CIFS client filesystem is not mounted, limiting exposure to systems configured to access remote SMB storage. While repeated reconnection attempts under heavy timeout conditions can exhaust internal request tracking and cause a denial of service, the flaw does not facilitate arbitrary code execution or data exposure.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.