CVE-2025-40084

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

ksmbd: transport_ipc: validate payload size before reading handle

handle_response() dereferences the payload as a 4-byte handle without verifying that the declared payload size is at least 4 bytes. A malformed or truncated message from ksmbd.mountd can lead to a 4-byte read past the declared payload size. Validate the size before dereferencing.

This is a minimal fix to guard the initial handle read.

This vulnerability poses no risk to Red Hat products because the in-kernel SMB server (ksmbd) is not shipped or supported in Red Hat Enterprise Linux. The flaw stems from insufficient payload length verification within the ksmbd inter-process communication handler, which could allow out-of-bounds memory reads upon receiving malformed responses from the mount daemon. Supported Red Hat kernel builds do not include the vulnerable code, preventing exposure to this flaw.