zram: fix out-of-bounds access in writeback_store()
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 4 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
In 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.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.160, 6.12.111, 6.18.57, 7.2.4, 7.3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 5 | Affected | No fix yet: Fix deferred |
Not affected: 4 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat OpenShift Container Platform 4
Timeline
- 2026-10-02 Threatist record created from CVE-2026-89718
- 2026-10-03 Alias added: GHSA-8g3j-f4r3-9992
- 2026-10-16 Fix available: Linux/[email protected], Linux/Linux@ef073edd7cfd31aeb90eeab23273102c601f4d8e · CNA
- 2026-10-16 1 new reference · CNA
- 2026-10-19 Fix available: Linux/[email protected] · CNA
- 2026-10-21 Fix available: Linux/[email protected], Linux/Linux@c2745e657f0974871fbc60d46d48c2b04e581330 · CNA
- 2026-10-21 1 new reference · CNA
- 2026-10-30 Fix available: Linux/[email protected], Linux/Linux@f1c5611f699a3aa2a85ebd5fec03dc9bc501e6d0 · CNA
- 2026-10-30 1 new reference · CNA
- 2026-11-06 Affected versions changed · Red Hat
References
Other 6
- https://git.kernel.org/stable/c/f1c5611f699a3aa2a85ebd5fec03dc9bc501e6d0
- https://git.kernel.org/stable/c/c2745e657f0974871fbc60d46d48c2b04e581330
- https://git.kernel.org/stable/c/4d82d60178b02797dbe529e01ac211b26670c49f
- https://git.kernel.org/stable/c/ef073edd7cfd31aeb90eeab23273102c601f4d8e
- https://git.kernel.org/stable/c/07a82a66f8c1894d92e51d97542c32ebf2c51b09
- https://git.kernel.org/stable/c/894913e2d35c46ff19a77530907771ae57862b96
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Sources
- CVE-2026-89718 · CVE Program
- CVE-2026-89718 · NVD
- FIRST EPSS
- GHSA-8g3j-f4r3-9992 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-89718 · Red Hat security data · CC BY 4.0
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