CVE-2024-56548

/// Technical description

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

hfsplus: don't query the device logical block size multiple times

Devices block sizes may change. One of these cases is a loop device by

using ioctl LOOP_SET_BLOCK_SIZE.

While this may cause other issues like IO being rejected, in the case of

hfsplus, it will allocate a block by using that size and potentially write

out-of-bounds when hfsplus_read_wrapper calls hfsplus_submit_bio and the

latter function reads a different io_size.

Using a new min_io_size initally set to sb_min_blocksize works for the

purposes of the original fix, since it will be set to the max between

HFSPLUS_SECTOR_SIZE and the first seen logical block size. We still use the

max between HFSPLUS_SECTOR_SIZE and min_io_size in case the latter is not

initialized.

Tested by mounting an hfsplus filesystem with loop block sizes 512, 1024

and 4096.

The produced KASAN report before the fix looks like this:

[ 419.944641] ===============================

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References