CVE-2026-43324

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> USB: dummy-hcd: Fix interrupt synchronization error<br /> <br /> This fixes an error in synchronization in the dummy-hcd driver. The<br /> error has a somewhat involved history. The synchronization mechanism<br /> was introduced by commit 7dbd8f4cabd9 ("USB: dummy-hcd: Fix erroneous<br /> synchronization change"), which added an emulated "interrupts enabled"<br /> flag together with code emulating synchronize_irq() (it waits until<br /> all current handler callbacks have returned).<br /> <br /> But the emulated interrupt-disable occurred too late, after the driver<br /> containing the handler callback routines had been told that it was<br /> unbound and no more callbacks would occur. Commit 4a5d797a9f9c ("usb:<br /> gadget: dummy_hcd: fix gpf in gadget_setup") tried to fix this by<br /> moving the synchronize_irq() emulation code from dummy_stop() to<br /> dummy_pullup(), which runs before the unbind callback.<br /> <br /> There still were races, though, because the emulated interrupt-disable<br /> still occurred too late. It couldn&amp;#39;t be moved to dummy_pullup(),<br /> because that routine can be called for reasons other than an impending<br /> unbind. Therefore commits 7dc0c55e9f30 ("USB: UDC core: Add<br /> udc_async_callbacks gadget op") and 04145a03db9d ("USB: UDC: Implement<br /> udc_async_callbacks in dummy-hcd") added an API allowing the UDC core<br /> to tell dummy-hcd exactly when emulated interrupts and their callbacks<br /> should be disabled.<br /> <br /> That brings us to the current state of things, which is still wrong<br /> because the emulated synchronize_irq() occurs before the emulated<br /> interrupt-disable! That&amp;#39;s no good, beause it means that more emulated<br /> interrupts can occur after the synchronize_irq() emulation has run,<br /> leading to the possibility that a callback handler may be running when<br /> the gadget driver is unbound.<br /> <br /> To fix this, we have to move the synchronize_irq() emulation code yet<br /> again, to the dummy_udc_async_callbacks() routine, which takes care of<br /> enabling and disabling emulated interrupt requests. The<br /> synchronization will now run immediately after emulated interrupts are<br /> disabled, which is where it belongs.