Bug 2507241 (CVE-2026-64292)

Summary: CVE-2026-64292 kernel: iommufd: Move vevent memory allocation outside spinlock
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's iommufd component. A local user can exploit this vulnerability by allocating large `veventq` queues, which are processed inside a spinlock. This can lead to the exhaustion of atomic memory reserves, resulting in a Denial of Service (DoS) condition.
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Description OSIDB Bzimport 2026-07-25 10:12:23 UTC 
In the Linux kernel, the following vulnerability has been resolved:

iommufd: Move vevent memory allocation outside spinlock

The veventq memory allocation happens inside the spinlock. Given its depth
is decided by the user space, this leaves a vulnerability, where userspace
can allocate large queues to exhaust atomic memory reserves.

Move the allocation outside the spinlock and use GFP_NOWAIT, which can fail
fast under memory pressure without dipping into the GFP_ATOMIC reserves or
direct-reclaiming from the threaded IRQ handler. On allocation failure,
queue the lost_events_header (so userspace learns of the drop) and return
-ENOMEM so the caller learns of the kernel-side memory pressure.

This is intentionally distinct from the queue-overflow path, which also
queues the lost_events_header but returns 0: a full queue is an expected
userspace-pacing condition rather than a kernel error.

A subsequent change will cap the upper bound of the veventq_depth.
Comment 1 TEJ RATHI 2026-07-29 08:35:26 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072504-CVE-2026-64292-322d@gregkh/T