fs/omfs: reject s_sys_blocksize smaller than OMFS_DIR_START

Summary

CVECVE-2026-53130
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-24 17:17:28 UTC
Updated2026-06-24 17:17:28 UTC
DescriptionIn 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.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected a3ab7155ea21aadc8a4d5687e91b3d876973185e fbc72f5c645155dc2ed3573243ed20f9913e3a54 git Not specified
CNA Linux Linux affected a3ab7155ea21aadc8a4d5687e91b3d876973185e 5822a05a841a10794ad818620dd2af490b0705d3 git Not specified
CNA Linux Linux affected a3ab7155ea21aadc8a4d5687e91b3d876973185e 754ff1bea3819a90c6f33cccfc1a299ef7609f07 git Not specified
CNA Linux Linux affected a3ab7155ea21aadc8a4d5687e91b3d876973185e 131ea3e57fc22936ed0e2c8330f2e36106172f51 git Not specified
CNA Linux Linux affected a3ab7155ea21aadc8a4d5687e91b3d876973185e 79f84af38c9fef9deb0e02c79eb969b5541c2644 git Not specified
CNA Linux Linux affected a3ab7155ea21aadc8a4d5687e91b3d876973185e 6561afc38398e3518a29c5eebb975c30468f98a6 git Not specified
CNA Linux Linux affected a3ab7155ea21aadc8a4d5687e91b3d876973185e 817f16ed62bc58a168417bfb5e859c2a370bab03 git Not specified
CNA Linux Linux affected a3ab7155ea21aadc8a4d5687e91b3d876973185e 0621c385fda1376e967f37ccd534c26c3e511d14 git Not specified
CNA Linux Linux affected 2.6.27 Not specified
CNA Linux Linux unaffected 2.6.27 semver Not specified
CNA Linux Linux unaffected 5.10.258 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.209 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.175 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.141 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.91 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.33 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.10 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/754ff1bea3819a90c6f33cccfc1a299ef7609f07 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/79f84af38c9fef9deb0e02c79eb969b5541c2644 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/817f16ed62bc58a168417bfb5e859c2a370bab03 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5822a05a841a10794ad818620dd2af490b0705d3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/131ea3e57fc22936ed0e2c8330f2e36106172f51 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fbc72f5c645155dc2ed3573243ed20f9913e3a54 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6561afc38398e3518a29c5eebb975c30468f98a6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0621c385fda1376e967f37ccd534c26c3e511d14 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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