gfs2: Validate i_depth for exhash directories

...

CVE-2025-38710

The CVE-2025-38710 vulnerability affects the Linux kernel GFS2: it relies on i_depth validation for exhash directories. A fuzzer introduced corruption that could yield a dir_e_read() depth of 0, causing an undefined shift by 32 at index = hash >> (32 - dip->i_depth). The minimum depth is...