UBUNTU-CVE-2026-43324
In 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.
02 / AFFECTED SOFTWARE
Affected packages
6 explicit affected versions
59 explicit affected versions
24 explicit affected versions
82 explicit affected versions
83 explicit affected versions
84 explicit affected versions
6 explicit affected versions
87 explicit affected versions
50 explicit affected versions
19 explicit affected versions
11 explicit affected versions
39 explicit affected versions
51 explicit affected versions
16 explicit affected versions
18 explicit affected versions
43 explicit affected versions
63 explicit affected versions
43 explicit affected versions
8 explicit affected versions
54 explicit affected versions
5 explicit affected versions
8 explicit affected versions
10 explicit affected versions
7 explicit affected versions
10 explicit affected versions
12 explicit affected versions
3 explicit affected versions
13 explicit affected versions
26 explicit affected versions
38 explicit affected versions
9 explicit affected versions
17 explicit affected versions
11 explicit affected versions
39 explicit affected versions
18 explicit affected versions
14 explicit affected versions
88 explicit affected versions
4 explicit affected versions
78 explicit affected versions
77 explicit affected versions
12 explicit affected versions
41 explicit affected versions
34 explicit affected versions
3 explicit affected versions
10 explicit affected versions
11 explicit affected versions
65 explicit affected versions
20 explicit affected versions
11 explicit affected versions
39 explicit affected versions
12 explicit affected versions
19 explicit affected versions
10 explicit affected versions
6 explicit affected versions
97 explicit affected versions
76 explicit affected versions
10 explicit affected versions
37 explicit affected versions
26 explicit affected versions
89 explicit affected versions
7 explicit affected versions
84 explicit affected versions
40 explicit affected versions
13 explicit affected versions
44 explicit affected versions
35 explicit affected versions
49 explicit affected versions
47 explicit affected versions
18 explicit affected versions
40 explicit affected versions
62 explicit affected versions
45 explicit affected versions
13 explicit affected versions
4 explicit affected versions
23 explicit affected versions
52 explicit affected versions
1 explicit affected versions
21 explicit affected versions
7 explicit affected versions
16 explicit affected versions
10 explicit affected versions
20 explicit affected versions
48 explicit affected versions
8 explicit affected versions
7 explicit affected versions
12 explicit affected versions
11 explicit affected versions
7 explicit affected versions
12 explicit affected versions
14 explicit affected versions
10 explicit affected versions
1 explicit affected versions
7 explicit affected versions
17 explicit affected versions
12 explicit affected versions
10 explicit affected versions
43 explicit affected versions
16 explicit affected versions
17 explicit affected versions
27 explicit affected versions
10 explicit affected versions
37 explicit affected versions
10 explicit affected versions
11 explicit affected versions
13 explicit affected versions
10 explicit affected versions
26 explicit affected versions
10 explicit affected versions
13 explicit affected versions
34 explicit affected versions
26 explicit affected versions
29 explicit affected versions
13 explicit affected versions
12 explicit affected versions
95 explicit affected versions
10 explicit affected versions
41 explicit affected versions
40 explicit affected versions
8 explicit affected versions
89 explicit affected versions
52 explicit affected versions
33 explicit affected versions
23 explicit affected versions
58 explicit affected versions
10 explicit affected versions
5 explicit affected versions
12 explicit affected versions
11 explicit affected versions
7 explicit affected versions
12 explicit affected versions
16 explicit affected versions
5 explicit affected versions
74 explicit affected versions
90 explicit affected versions
10 explicit affected versions
1 explicit affected versions
66 explicit affected versions
35 explicit affected versions
48 explicit affected versions
11 explicit affected versions
13 explicit affected versions
46 explicit affected versions
16 explicit affected versions
88 explicit affected versions
50 explicit affected versions
3 explicit affected versions
7 explicit affected versions
2 explicit affected versions
15 explicit affected versions
12 explicit affected versions
70 explicit affected versions
77 explicit affected versions
7 explicit affected versions
27 explicit affected versions
46 explicit affected versions
13 explicit affected versions
13 explicit affected versions
7 explicit affected versions
8 explicit affected versions
9 explicit affected versions
36 explicit affected versions
44 explicit affected versions
16 explicit affected versions
45 explicit affected versions
37 explicit affected versions
50 explicit affected versions
14 explicit affected versions
39 explicit affected versions
90 explicit affected versions
6 explicit affected versions
7 explicit affected versions
4 explicit affected versions
79 explicit affected versions
10 explicit affected versions
1 explicit affected versions
1 explicit affected versions
1 explicit affected versions
78 explicit affected versions
78 explicit affected versions
13 explicit affected versions
43 explicit affected versions
16 explicit affected versions
10 explicit affected versions
8 explicit affected versions
45 explicit affected versions
14 explicit affected versions
14 explicit affected versions
11 explicit affected versions
1 explicit affected versions
19 explicit affected versions
1 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In 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.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/2ca9e46f8f1f5a297eb0ac83f79d35d5b3a02541
- https://git.kernel.org/stable/c/2ca9e46f8f1f5a297eb0ac83f79d35d5b3a02541
- https://git.kernel.org/stable/c/5687a09776069bd915560021c9728ca528440128
- https://git.kernel.org/stable/c/5aa776c8615bea3b1eaeec87b0788375800ead4f
- https://git.kernel.org/stable/c/8bcd80219d8e10e660bf29b20e41bb8beb4e4cb7
- https://git.kernel.org/stable/c/94d4fab1dd9e64f45449bcc7d6a5acf796b13015
- https://git.kernel.org/stable/c/cbf7df5e5d27cd5bea92ee9a75a4b28dbcc718d4
- https://git.kernel.org/stable/c/d847f375b1bcea713143bc02720d13d2d01b012a
- https://ubuntu.com/security/CVE-2026-43324
- https://ubuntu.com/security/notices/USN-8567-1
- https://ubuntu.com/security/notices/USN-8574-1
- https://ubuntu.com/security/notices/USN-8574-2
- https://ubuntu.com/security/notices/USN-8574-3
- https://ubuntu.com/security/notices/USN-8575-1
- https://ubuntu.com/security/notices/USN-8575-2
- https://ubuntu.com/security/notices/USN-8575-3
- https://ubuntu.com/security/notices/USN-8576-1
- https://ubuntu.com/security/notices/USN-8576-2
- https://ubuntu.com/security/notices/USN-8595-1
- https://ubuntu.com/security/notices/USN-8595-2
- https://ubuntu.com/security/notices/USN-8595-3
- https://ubuntu.com/security/notices/USN-8596-1
- https://ubuntu.com/security/notices/USN-8606-1
- https://ubuntu.com/security/notices/USN-8607-1
- https://ubuntu.com/security/notices/USN-8608-1
- https://ubuntu.com/security/notices/USN-8609-1
- https://ubuntu.com/security/notices/USN-8610-1
- https://ubuntu.com/security/notices/USN-8619-1
- https://ubuntu.com/security/notices/USN-8620-1
- https://ubuntu.com/security/notices/USN-8620-2
- https://ubuntu.com/security/notices/USN-8620-3
- https://ubuntu.com/security/notices/USN-8620-4
- https://www.cve.org/CVERecord?id=CVE-2026-43324