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

minix: avoid overflow in bitmap block count calculation

minix_check_superblock() uses minix_blocks_needed() to verify that the
on-disk imap and zmap block counts are large enough for the advertised
inode and zone counts.

The helper currently performs DIV_ROUND_UP() in unsigned int arithmetic.
A Minix v3 image can set s_ninodes or s_zones near UINT_MAX so the
addition inside DIV_ROUND_UP() wraps to zero. That makes a zero imap/zmap
block count look valid, after which minix_fill_super() can dereference
s_imap[0] or s_zmap[0] even though no bitmap buffers were allocated.

Impact: mounting a crafted Minix v3 image whose s_ninodes or s_zones is
near UINT_MAX makes minix_check_superblock() accept a zero bitmap-block
count and minix_fill_super() dereference s_imap[0]/s_zmap[0], panicking
the kernel.

The divisor is the bitmap capacity in bits, blocksize * 8, which is
always a power of two: minix_fill_super() obtains the block size through
sb_set_blocksize(), and blk_validate_block_size() rejects any size that
is not a power of two. Use DIV_ROUND_UP_POW2(), which divides before
adding the round-up term and so cannot overflow for a power-of-two
divisor.
Published: 2026-08-15
Score: n/a
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
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Remediation

No vendor fix or workaround currently provided.

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History

Sat, 15 Aug 2026 11:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-190

Sat, 15 Aug 2026 06:00:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: minix: avoid overflow in bitmap block count calculation minix_check_superblock() uses minix_blocks_needed() to verify that the on-disk imap and zmap block counts are large enough for the advertised inode and zone counts. The helper currently performs DIV_ROUND_UP() in unsigned int arithmetic. A Minix v3 image can set s_ninodes or s_zones near UINT_MAX so the addition inside DIV_ROUND_UP() wraps to zero. That makes a zero imap/zmap block count look valid, after which minix_fill_super() can dereference s_imap[0] or s_zmap[0] even though no bitmap buffers were allocated. Impact: mounting a crafted Minix v3 image whose s_ninodes or s_zones is near UINT_MAX makes minix_check_superblock() accept a zero bitmap-block count and minix_fill_super() dereference s_imap[0]/s_zmap[0], panicking the kernel. The divisor is the bitmap capacity in bits, blocksize * 8, which is always a power of two: minix_fill_super() obtains the block size through sb_set_blocksize(), and blk_validate_block_size() rejects any size that is not a power of two. Use DIV_ROUND_UP_POW2(), which divides before adding the round-up term and so cannot overflow for a power-of-two divisor.
Title minix: avoid overflow in bitmap block count calculation
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-08-15T05:56:05.995Z

Reserved: 2026-08-09T03:40:39.922Z

Link: CVE-2026-72369

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-15T06:22:10.340

Modified: 2026-08-15T06:22:10.340

Link: CVE-2026-72369

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-08-15T11:30:07Z

Weaknesses
  • CWE-190

    Integer Overflow or Wraparound