CVE-2026-89965

nvdimm/btt: reject an arena whose nfree is below the lane count

State: Published
Severity: 7.8 High
Published: Sep 16, 2026
Updated: Oct 19, 2026
Reserved: Sep 11, 2026

Description

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

nvdimm/btt: reject an arena whose nfree is below the lane count

The BTT info block's nfree field, the number of reserve free blocks, is read from the medium without validation. btt_freelist_init() and btt_rtt_init() size the per-lane freelist[] and rtt[] arrays by nfree, but the I/O path indexes them by the lane from nd_region_acquire_lane(), which is bounded by nd_region->num_lanes (ND_MAX_LANES), not by nfree. A crafted or foreign arena whose nfree is below the lane count makes freelist[lane]/rtt[lane] run past the allocation: an out-of-bounds write.

btt.rst documents the nlanes = min(nfree, num_cpus) invariant, which the code does not currently honor: num_lanes is ND_MAX_LANES regardless of nfree. Reject an arena whose nfree is below num_lanes at discovery, before the per-lane arrays are allocated, enforcing that invariant.

Scores

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

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	5212e11fde4d40fa627668b4f2222d20db488f71 to before eb491343d2d1784121ad9af91c25b338c28913c3Affected 5212e11fde4d40fa627668b4f2222d20db488f71 to before 59d5cd1f42b4bab3609512c3cb3d3540d3d21da7Affected 5212e11fde4d40fa627668b4f2222d20db488f71 to before f6c5313aae794ecca8f762c1a3493de5c266f120Affected 5212e11fde4d40fa627668b4f2222d20db488f71 to before f9bf05c63b77d000e9c01f3e47af36973887d350Affected 5212e11fde4d40fa627668b4f2222d20db488f71 to before 6f79d1a5f2611a3d36e9312be5425cd9cb397c51Affected 5212e11fde4d40fa627668b4f2222d20db488f71 to before 6b1faf1f099f7060b5f1f2f0d024132581f1726eAffected 5212e11fde4d40fa627668b4f2222d20db488f71 to before 9dfa11cef4750b67591307f2c62e47a23d60e4b7Affected 5212e11fde4d40fa627668b4f2222d20db488f71 to before 6a1f2e5ed9267ca19187038ac635393c165213acAffected
LinuxLinux	4.2Affected before 4.2Not affected 5.10.270 through 5.10.Not affected 5.15.221 through 5.15.Not affected 6.1.188 through 6.1.Not affected 6.6.157 through 6.6.Not affected 6.12.110 through 6.12.Not affected 6.18.51 through 6.18.Not affected 7.2.5 through 7.2.*Not affected 7.3 and laterNot affected

Product

Versions

LinuxLinux

5212e11fde4d40fa627668b4f2222d20db488f71 to before eb491343d2d1784121ad9af91c25b338c28913c3Affected
5212e11fde4d40fa627668b4f2222d20db488f71 to before 59d5cd1f42b4bab3609512c3cb3d3540d3d21da7Affected
5212e11fde4d40fa627668b4f2222d20db488f71 to before f6c5313aae794ecca8f762c1a3493de5c266f120Affected
5212e11fde4d40fa627668b4f2222d20db488f71 to before f9bf05c63b77d000e9c01f3e47af36973887d350Affected
5212e11fde4d40fa627668b4f2222d20db488f71 to before 6f79d1a5f2611a3d36e9312be5425cd9cb397c51Affected
5212e11fde4d40fa627668b4f2222d20db488f71 to before 6b1faf1f099f7060b5f1f2f0d024132581f1726eAffected
5212e11fde4d40fa627668b4f2222d20db488f71 to before 9dfa11cef4750b67591307f2c62e47a23d60e4b7Affected
5212e11fde4d40fa627668b4f2222d20db488f71 to before 6a1f2e5ed9267ca19187038ac635393c165213acAffected

LinuxLinux

4.2Affected
before 4.2Not affected
5.10.270 through 5.10.*Not affected
5.15.221 through 5.15.*Not affected
6.1.188 through 6.1.*Not affected
6.6.157 through 6.6.*Not affected
6.12.110 through 6.12.*Not affected
6.18.51 through 6.18.*Not affected
7.2.5 through 7.2.*Not affected
7.3 and laterNot affected

References

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