CVE-2026-53130 – fs/omfs: reject s_sys_blocksize smaller than OMFS_DIR_START

CVE ID :CVE-2026-53130

Published : June 24, 2026, 4:30 p.m. | 1 hour, 13 minutes ago

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

fs/omfs: reject s_sys_blocksize smaller than OMFS_DIR_START

omfs_fill_super() rejects oversized s_sys_blocksize values (> PAGE_SIZE),
but it does not reject values smaller than OMFS_DIR_START (0x1b8 = 440).

Later, omfs_make_empty() uses

sbi->s_sys_blocksize – OMFS_DIR_START

as the length argument to memset(). Since s_sys_blocksize is u32,
a crafted filesystem image with s_sys_blocksize b_data + OMFS_DIR_START and overwrites kernel
memory far beyond the backing block buffer.

Add the corresponding lower-bound check alongside the existing upper-bound
check in omfs_fill_super(), so that malformed images are rejected during
superblock validation before any filesystem data is processed.

Severity: 0.0 | NA

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