Advisory [CVE-2026-64361] fix u32 overflow in check_and_correct_requested_length

In the Linux kernel, the following vulnerability has been resolved: hfs/hfsplus: fix u32 overflow in check_and_correct_requested_length check_and_correct_requested_length() compares (off + len) against node_size using u32 arithmetic.

When the caller passes a large len value (e.g. from an underflowed subtraction in hfs_brec_remove()), off + len can wrap past 2^32 and produce a small result, causing the bounds check to pass when it should fail.

For example, with off=14 and len=0xFFFFFFF2 (underflowed from data_off - keyoffset - size in hfs_brec_remove), off + len wraps to 6, which is less than a typical node_size of 512, so the check passes and the subsequent memmove reads ~4GB past the node buffer. Fix this by widening the addition to u64 before comparing against node_size.

This prevents the u32 wrap while keeping the logic straightforward. A flaw was found in the Linux kernel's HFS/HFS+ filesystem driver.

An integer overflow vulnerability exists in the `check_and_correct_requested_length` function, where a calculation involving `off + len` can wrap around due to 32-bit arithmetic. This allows an attacker to bypass bounds checks, leading to an out-of-bounds read of approximately 4GB of memory.

A local attacker with low privileges could exploit this to potentially disclose sensitive information or cause memory corruption. Red Hat severity: not rated.

Weakness: CWE-125.