zram: fix out-of-bounds access in writeback_store()

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Summary

CVECVE-2026-89718
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:59 UTC
Updated2026-09-11 20:19:59 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: zram: fix out-of-bounds access in writeback_store() Patch series "zram: fix stale scan bounds after reinitialization". Both writeback_store() and read_block_state() derive their table scan bounds from zram->disksize before acquiring dev_lock. If the device is reset and reinitialized with a smaller disksize between that read and lock acquisition, the bound can describe the old table while the scan operates on the new one. This can lead to out-of-bounds slot accesses. Move both bound calculations under dev_lock so each bound remains consistent with the table throughout its scan. Keep the fixes separate because the affected interfaces originate from different commits and can be backported independently. This patch (of 2): writeback_store() calculates the table scan bounds before taking dev_lock. A reset followed by reconfiguration with a smaller disksize can therefore replace zram->table while writeback_store() is waiting for the lock. Once it acquires the lock, it sees an initialized device but scans the new table using the old upper bound, resulting in an out-of-bounds access. Calculate the number of pages while holding dev_lock so the scan bound matches the table protected by the lock.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected a939888ec38bf1f33e4a903056677e92a4844244 07a82a66f8c1894d92e51d97542c32ebf2c51b09 git Not specified
CNA Linux Linux affected a939888ec38bf1f33e4a903056677e92a4844244 894913e2d35c46ff19a77530907771ae57862b96 git Not specified
CNA Linux Linux affected 5.0 Not specified
CNA Linux Linux unaffected 5.0 semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/07a82a66f8c1894d92e51d97542c32ebf2c51b09 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/894913e2d35c46ff19a77530907771ae57862b96 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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