CVE-2026-53130

fs/omfs: reject s_sys_blocksize smaller than OMFS_DIR_START

State: Published
Severity: 7.8 High
Published: Jun 24, 2026
Updated: Aug 5, 2026
Reserved: Jun 9, 2026

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 < OMFS_DIR_START causes an unsigned underflow there, wrapping to a value near 2^32. That drives a ~4 GiB memset() from bh->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.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	a3ab7155ea21aadc8a4d5687e91b3d876973185e to before fbc72f5c645155dc2ed3573243ed20f9913e3a54Affected a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 5822a05a841a10794ad818620dd2af490b0705d3Affected a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 754ff1bea3819a90c6f33cccfc1a299ef7609f07Affected a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 131ea3e57fc22936ed0e2c8330f2e36106172f51Affected a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 79f84af38c9fef9deb0e02c79eb969b5541c2644Affected a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 6561afc38398e3518a29c5eebb975c30468f98a6Affected a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 817f16ed62bc58a168417bfb5e859c2a370bab03Affected a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 0621c385fda1376e967f37ccd534c26c3e511d14Affected
LinuxLinux	2.6.27Affected before 2.6.27Not affected 5.10.258 through 5.10.Not affected 5.15.209 through 5.15.Not affected 6.1.175 through 6.1.Not affected 6.6.141 through 6.6.Not affected 6.12.91 through 6.12.Not affected 6.18.33 through 6.18.Not affected 7.0.10 through 7.0.*Not affected 7.1 and laterNot affected

Product

Versions

LinuxLinux

a3ab7155ea21aadc8a4d5687e91b3d876973185e to before fbc72f5c645155dc2ed3573243ed20f9913e3a54Affected
a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 5822a05a841a10794ad818620dd2af490b0705d3Affected
a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 754ff1bea3819a90c6f33cccfc1a299ef7609f07Affected
a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 131ea3e57fc22936ed0e2c8330f2e36106172f51Affected
a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 79f84af38c9fef9deb0e02c79eb969b5541c2644Affected
a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 6561afc38398e3518a29c5eebb975c30468f98a6Affected
a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 817f16ed62bc58a168417bfb5e859c2a370bab03Affected
a3ab7155ea21aadc8a4d5687e91b3d876973185e to before 0621c385fda1376e967f37ccd534c26c3e511d14Affected

LinuxLinux

2.6.27Affected
before 2.6.27Not affected
5.10.258 through 5.10.*Not affected
5.15.209 through 5.15.*Not affected
6.1.175 through 6.1.*Not affected
6.6.141 through 6.6.*Not affected
6.12.91 through 6.12.*Not affected
6.18.33 through 6.18.*Not affected
7.0.10 through 7.0.*Not affected
7.1 and laterNot affected

References

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