uio_hv_generic: Let userspace take care of interrupt mask

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-40048
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-10-28 12:15:38 UTC
Updated2026-07-30 06:24:08 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: uio_hv_generic: Let userspace take care of interrupt mask Remove the logic to set interrupt mask by default in uio_hv_generic driver as the interrupt mask value is supposed to be controlled completely by the user space. If the mask bit gets changed by the driver, concurrently with user mode operating on the ring, the mask bit may be set when it is supposed to be clear, and the user-mode driver will miss an interrupt which will cause a hang. For eg- when the driver sets inbound ring buffer interrupt mask to 1, the host does not interrupt the guest on the UIO VMBus channel. However, setting the mask does not prevent the host from putting a message in the inbound ring buffer. So let’s assume that happens, the host puts a message into the ring buffer but does not interrupt. Subsequently, the user space code in the guest sets the inbound ring buffer interrupt mask to 0, saying “Hey, I’m ready for interrupts”. User space code then calls pread() to wait for an interrupt. Then one of two things happens: * The host never sends another message. So the pread() waits forever. * The host does send another message. But because there’s already a message in the ring buffer, it doesn’t generate an interrupt. This is the correct behavior, because the host should only send an interrupt when the inbound ring buffer transitions from empty to not-empty. Adding an additional message to a ring buffer that is not empty is not supposed to generate an interrupt on the guest. Since the guest is waiting in pread() and not removing messages from the ring buffer, the pread() waits forever. This could be easily reproduced in hv_fcopy_uio_daemon if we delay setting interrupt mask to 0. Similarly if hv_uio_channel_cb() sets the interrupt_mask to 1, there’s a race condition. Once user space empties the inbound ring buffer, but before user space sets interrupt_mask to 0, the host could put another message in the ring buffer but it wouldn’t interrupt. Then the next pread() would hang. Fix these by removing all instances where interrupt_mask is changed, while keeping the one in set_event() unchanged to enable userspace control the interrupt mask by writing 0/1 to /dev/uioX.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS: 0.006000000 probability, percentile 0.453600000 (date 2026-07-31)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 95096f2fbd10186d3e78a328b327afc71428f65f 540aac117eaea5723cef5e4cbf3035c4ac654d92 git Not specified
CNA Linux Linux affected 95096f2fbd10186d3e78a328b327afc71428f65f 65d40acd911c7011745cbbd2aaac34eb5266d11e git Not specified
CNA Linux Linux affected 95096f2fbd10186d3e78a328b327afc71428f65f a44f61f878f32071d6378e8dd7c2d47f9490c8f7 git Not specified
CNA Linux Linux affected 95096f2fbd10186d3e78a328b327afc71428f65f 01ce972e6f9974a7c76943bcb7e93746917db83a git Not specified
CNA Linux Linux affected 95096f2fbd10186d3e78a328b327afc71428f65f 2af39ab5e6dc46b835a52e80a22d0cad430985e3 git Not specified
CNA Linux Linux affected 95096f2fbd10186d3e78a328b327afc71428f65f 37bd91f22794dc05436130d6983302cb90ecfe7e git Not specified
CNA Linux Linux affected 95096f2fbd10186d3e78a328b327afc71428f65f e29587c07537929684faa365027f4b0d87521e1b git Not specified
CNA Linux Linux affected 95096f2fbd10186d3e78a328b327afc71428f65f b15b7d2a1b09ef5428a8db260251897405a19496 git Not specified
CNA Linux Linux affected 4.10 Not specified
CNA Linux Linux unaffected 4.10 semver Not specified
CNA Linux Linux unaffected 5.4.301 5.4.* semver Not specified
CNA Linux Linux unaffected 5.10.246 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.195 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.156 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.112 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.53 6.12.* semver Not specified
CNA Linux Linux unaffected 6.17.3 6.17.* semver Not specified
CNA Linux Linux unaffected 6.18 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/b15b7d2a1b09ef5428a8db260251897405a19496 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/540aac117eaea5723cef5e4cbf3035c4ac654d92 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e29587c07537929684faa365027f4b0d87521e1b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a44f61f878f32071d6378e8dd7c2d47f9490c8f7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2af39ab5e6dc46b835a52e80a22d0cad430985e3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/37bd91f22794dc05436130d6983302cb90ecfe7e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/65d40acd911c7011745cbbd2aaac34eb5266d11e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/01ce972e6f9974a7c76943bcb7e93746917db83a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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