Bug 2536454 (CVE-2026-93074)

Summary: CVE-2026-93074 kernel: dax/fsdev: use __va(phys) for kaddr in direct_access
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in the Linux kernel's `dax/fsdev` component. An error in calculating kernel virtual addresses within the `__fsdev_dax_direct_access()` function, specifically for multi-range devices with physical gaps, can lead to incorrect memory addressing. This issue could result in memory corruption, potentially affecting system stability or leading to unintended memory access.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-17 17:59:54 UTC 
In the Linux kernel, the following vulnerability has been resolved:

dax/fsdev: use __va(phys) for kaddr in direct_access

Use __va(phys) instead of virt_addr + linear_offset for the kaddr
return in __fsdev_dax_direct_access(). The previous code added a
device-linear byte offset to virt_addr (which is __va of ranges[0]),
but for multi-range devices with physical gaps between ranges, this
linear arithmetic crosses the gap and produces a wrong kernel virtual
address. Using __va(phys) where phys comes from dax_pgoff_to_phys()
is correct for any range layout because the direct map translates
each physical address independently.

This leaves dev_dax->virt_addr write-only, so remove the field
(suggested by Dave Jiang).
Comment 1 gkamathe 2026-09-19 22:52:22 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93074.mbox