CVE-2026-89965
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.
How to fix
- Linux Linuxeb491343d2d1784121ad9af91c25b338c28913c3, 59d5cd1f42b4bab3609512c3cb3d3540d3d21da7, f6c5313aae794ecca8f762c1a3493de5c266f120, f9bf05c63b77d000e9c01f3e47af36973887d350, 6f79d1a5f2611a3d36e9312be5425cd9cb397c51, 6b1faf1f099f7060b5f1f2f0d024132581f1726e, 9dfa11cef4750b67591307f2c62e47a23d60e4b7, 6a1f2e5ed9267ca19187038ac635393c165213ac or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| Linux Linux | 5212e11fde4d40fa627668b4f2222d20db488f71 ≤ v < eb491343d2d1784121ad9af91c25b338c28913c3, 5212e11fde4d40fa627668b4f2222d20db488f71 ≤ v < 59d5cd1f42b4bab3609512c3cb3d3540d3d21da7, 5212e11fde4d40fa627668b4f2222d20db488f71 ≤ v < f6c5313aae794ecca8f762c1a3493de5c266f120, 5212e11fde4d40fa627668b4f2222d20db488f71 ≤ v < f9bf05c63b77d000e9c01f3e47af36973887d350, 5212e11fde4d40fa627668b4f2222d20db488f71 ≤ v < 6f79d1a5f2611a3d36e9312be5425cd9cb397c51, 5212e11fde4d40fa627668b4f2222d20db488f71 ≤ v < 6b1faf1f099f7060b5f1f2f0d024132581f1726e, 5212e11fde4d40fa627668b4f2222d20db488f71 ≤ v < 9dfa11cef4750b67591307f2c62e47a23d60e4b7, 5212e11fde4d40fa627668b4f2222d20db488f71 ≤ v < 6a1f2e5ed9267ca19187038ac635393c165213ac, 4.2 | eb491343d2d1784121ad9af91c25b338c28913c3, 59d5cd1f42b4bab3609512c3cb3d3540d3d21da7, f6c5313aae794ecca8f762c1a3493de5c266f120, f9bf05c63b77d000e9c01f3e47af36973887d350, 6f79d1a5f2611a3d36e9312be5425cd9cb397c51, 6b1faf1f099f7060b5f1f2f0d024132581f1726e, 9dfa11cef4750b67591307f2c62e47a23d60e4b7, 6a1f2e5ed9267ca19187038ac635393c165213ac |
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