CVE-2026-98262

ata: libahci: clear PxCLBU and PxFBU for AHCI_HFLAG_32BIT_ONLY

State: Published
Severity: Not scored
Published: Oct 6, 2026
Updated: Oct 19, 2026
Reserved: Sep 25, 2026

Description

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

ata: libahci: clear PxCLBU and PxFBU for AHCI_HFLAG_32BIT_ONLY

A user reported that commit 105c42566a55 ("ata: ahci: force 32-bit DMA for JMicron JMB582/JMB585") made the JMicron JMB585 unusable on his board.

The failure is seen as soon as the ahci driver is probed, and booting with iommu=off does not solve the problem.

Looking at the AHCI specification, PxCLBU and PxFBU are both read only '0' for HBAs that do not support 64-bit addressing.

For HBAs that do support 64-bit addressing, the registers are read write, with a reset value that is Implementation Specific.

When using the AHCI_HFLAG_32BIT_ONLY flag, the HBA does support 64-bit addressing, and a 32-bit DMA mask is set by simply clearing HOST_CAP_64. Thus, in this case, we need to explicitly clear the registers to 0.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before 0191c9ff23ef1678dbfb5ad253a2dee92feb5d71Affected c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before 8f510f68208a1f673d7c7234a687be4671490e9cAffected c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before 4719424bb7cb9f20b73986bcb72dd528f0e5c6ebAffected c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before a5a8b4737f68bbac8aa0685af0c8921e6003c22bAffected c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before b28a17d4a9bb0aa38b48681c3927b012ba40eabeAffected c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before b691a3e244278362e552439d6d3ee5a5d3703488Affected c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before 7912ad8fb5233bb8cfe21d50df639c7f4854ff9dAffected c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before 82e47533221d4746947b74d2e79a478c36c6433aAffected
LinuxLinux	2.6.22Affected before 2.6.22Not affected 5.10.271 through 5.10.Not affected 5.15.222 through 5.15.Not affected 6.1.189 through 6.1.Not affected 6.6.158 through 6.6.Not affected 6.12.112 through 6.12.Not affected 6.18.54 through 6.18.Not affected 7.2.8 through 7.2.*Not affected 7.3 and laterNot affected

Product

Versions

LinuxLinux

c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before 0191c9ff23ef1678dbfb5ad253a2dee92feb5d71Affected
c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before 8f510f68208a1f673d7c7234a687be4671490e9cAffected
c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before 4719424bb7cb9f20b73986bcb72dd528f0e5c6ebAffected
c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before a5a8b4737f68bbac8aa0685af0c8921e6003c22bAffected
c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before b28a17d4a9bb0aa38b48681c3927b012ba40eabeAffected
c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before b691a3e244278362e552439d6d3ee5a5d3703488Affected
c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before 7912ad8fb5233bb8cfe21d50df639c7f4854ff9dAffected
c7a42156d99bcea7f8173ba7a6034bbaa2ecb77c to before 82e47533221d4746947b74d2e79a478c36c6433aAffected

LinuxLinux

2.6.22Affected
before 2.6.22Not affected
5.10.271 through 5.10.*Not affected
5.15.222 through 5.15.*Not affected
6.1.189 through 6.1.*Not affected
6.6.158 through 6.6.*Not affected
6.12.112 through 6.12.*Not affected
6.18.54 through 6.18.*Not affected
7.2.8 through 7.2.*Not affected
7.3 and laterNot affected

References

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