REDHAT-BUG-2467015: High severity Linux Linux kernel vulnerability

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

fs/smb/client: fix out-of-bounds read in cifssanitizeprepath

When cifssanitizeprepath is called with an empty string or a string containing only delimiters (e.g., "/"), the current logic attempts to check (cursor2 - 1) before cursor2 has advanced. This results in an out-of-bounds read.

This patch adds an early exit check after stripping prepended delimiters. If no path content remains, the function returns NULL.

The bug was identified via manual audit and verified using a standalone test case compiled with AddressSanitizer, which triggered a SEGV on affected inputs.