USB: dummy-hcd: Fix interrupt synchronization error

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Summary

CVECVE-2026-43324
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-08 14:16:41 UTC
Updated2026-05-11 08:16:09 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: USB: dummy-hcd: Fix interrupt synchronization error This fixes an error in synchronization in the dummy-hcd driver. The error has a somewhat involved history. The synchronization mechanism was introduced by commit 7dbd8f4cabd9 ("USB: dummy-hcd: Fix erroneous synchronization change"), which added an emulated "interrupts enabled" flag together with code emulating synchronize_irq() (it waits until all current handler callbacks have returned). But the emulated interrupt-disable occurred too late, after the driver containing the handler callback routines had been told that it was unbound and no more callbacks would occur. Commit 4a5d797a9f9c ("usb: gadget: dummy_hcd: fix gpf in gadget_setup") tried to fix this by moving the synchronize_irq() emulation code from dummy_stop() to dummy_pullup(), which runs before the unbind callback. There still were races, though, because the emulated interrupt-disable still occurred too late. It couldn't be moved to dummy_pullup(), because that routine can be called for reasons other than an impending unbind. Therefore commits 7dc0c55e9f30 ("USB: UDC core: Add udc_async_callbacks gadget op") and 04145a03db9d ("USB: UDC: Implement udc_async_callbacks in dummy-hcd") added an API allowing the UDC core to tell dummy-hcd exactly when emulated interrupts and their callbacks should be disabled. That brings us to the current state of things, which is still wrong because the emulated synchronize_irq() occurs before the emulated interrupt-disable! That's no good, beause it means that more emulated interrupts can occur after the synchronize_irq() emulation has run, leading to the possibility that a callback handler may be running when the gadget driver is unbound. To fix this, we have to move the synchronize_irq() emulation code yet again, to the dummy_udc_async_callbacks() routine, which takes care of enabling and disabling emulated interrupt requests. The synchronization will now run immediately after emulated interrupts are disabled, which is where it belongs.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.000240000 probability, percentile 0.070400000 (date 2026-05-10)

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

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 04145a03db9d78469e0817ab3a767c76c0fb0947 d847f375b1bcea713143bc02720d13d2d01b012a git Not specified
CNA Linux Linux affected 04145a03db9d78469e0817ab3a767c76c0fb0947 cbf7df5e5d27cd5bea92ee9a75a4b28dbcc718d4 git Not specified
CNA Linux Linux affected 04145a03db9d78469e0817ab3a767c76c0fb0947 5aa776c8615bea3b1eaeec87b0788375800ead4f git Not specified
CNA Linux Linux affected 04145a03db9d78469e0817ab3a767c76c0fb0947 94d4fab1dd9e64f45449bcc7d6a5acf796b13015 git Not specified
CNA Linux Linux affected 04145a03db9d78469e0817ab3a767c76c0fb0947 5687a09776069bd915560021c9728ca528440128 git Not specified
CNA Linux Linux affected 04145a03db9d78469e0817ab3a767c76c0fb0947 8bcd80219d8e10e660bf29b20e41bb8beb4e4cb7 git Not specified
CNA Linux Linux affected 04145a03db9d78469e0817ab3a767c76c0fb0947 2ca9e46f8f1f5a297eb0ac83f79d35d5b3a02541 git Not specified
CNA Linux Linux affected 5.14 Not specified
CNA Linux Linux unaffected 5.14 semver Not specified
CNA Linux Linux unaffected 5.15.203 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.168 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.134 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.81 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.22 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.12 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/cbf7df5e5d27cd5bea92ee9a75a4b28dbcc718d4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d847f375b1bcea713143bc02720d13d2d01b012a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2ca9e46f8f1f5a297eb0ac83f79d35d5b3a02541 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5aa776c8615bea3b1eaeec87b0788375800ead4f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/94d4fab1dd9e64f45449bcc7d6a5acf796b13015 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5687a09776069bd915560021c9728ca528440128 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8bcd80219d8e10e660bf29b20e41bb8beb4e4cb7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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