Bug 2406773 (CVE-2025-40056)

Summary: CVE-2025-40056 kernel: Linux kernel: Data corruption and denial of service in vhost/vringh due to improper copy_to_iter return value check
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in the Linux kernel's vhost/vringh component. This vulnerability arises from an improper check of the `copy_to_iter()` function's return value, which could lead to the system processing partially copied data. A local attacker with access to the vhost/virtio path (such as root or a user in the kvm/vhost group) could exploit this to cause data corruption or trigger a kernel fault, leading to a denial of service.
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Description OSIDB Bzimport 2025-10-28 12:04:45 UTC 
In the Linux kernel, the following vulnerability has been resolved:

vhost: vringh: Fix copy_to_iter return value check

The return value of copy_to_iter can't be negative, check whether the
copied length is equal to the requested length instead of checking for
negative values.
Comment 1 Jon Moroney 2025-10-28 20:41:03 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025102815-CVE-2025-40056-0a6b@gregkh/T