A vulnerability in the Linux kernel SMB client related to the fiemap ioctl handling allows a wild read from an empty truncated response from a malicious SMB2 server. The flaw occurs when the server returns a STATUS_BUFFER_OVERFLOW with an empty output, causing the client to read memory before a NULL pointer, potentially leading to a kernel oops (crash). The issue has been fixed by rejecting empty truncated range blobs and adding checks to prevent infinite loops or underflows.