What’s Vulnerable › Vulnerabilities

CVE-2026-90391: lib/test_hmm: fail dmirror_fault() when the mirrored mm is gone

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-17 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: lib/test_hmm: fail dmirror_fault() when the mirrored mm is gone dmirror_fault() is called from the dmirror_read() and dmirror_write() retry loops after dmirror_do_read() or dmirror_do_write() finds a missing device page table entry. If the mirrored mm has already exited, mmget_not_zero() fails. The current code returns 0 in that case, which tells the caller that faulting succeeded even though no page was faulted and no device page table entry was installed. The caller then retries the same address, hits -ENOENT again, and can loop forever without making progress. Return -EFAULT instead, so the ioctl fails when the mirrored mm is no longer faultable.

Affected products

• Linux kernel: 5.8 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/2636569ea7c19d9a40db4a1e8d0a027bdacf1569
• https://git.kernel.org/stable/c/50606ced303782f8715e2d0b98ca374ea498fa29
• https://git.kernel.org/stable/c/541a67f21ab807c8dbc0ea88d5a2eb73b2618090
• https://git.kernel.org/stable/c/6a8024511ddf4877435c34fb3d6028aa8e590649
• https://git.kernel.org/stable/c/701347e31aa607f3782403151a3125729d685275
• https://git.kernel.org/stable/c/a2074f86fc9653831e4fb7b711bb715db330f182
• https://git.kernel.org/stable/c/af7a6d6ec36a16a583ba2e4e9984c3cf1fe34655
• https://git.kernel.org/stable/c/d8e64ffab01e032ae29159d27230ace8cf8bdc80

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