UBUNTU-CVE-2026-68182: Medium severity ubuntu/linux vulnerability
In the Linux kernel, the following vulnerability has been resolved: comedi: comediparport: deal with premature interrupt Syzbot reported a general protection fault in comedigetissubdevicerunning(), which was called from the interrupt handler parportinterrupt() in the "comediparport" driver, but it does not currently have a C reproducer for the problem. It's probably due to a premature interrupt for one of two reasons: 1. The driver sets up the interrupt handler before the comedi subdevices used by the interrupt handler have been allocated, but does not disable the interrupt in the parallel port's CTRL register first. 2. The driver uses a user-supplied I/O port base address which Syzbot would have supplied, but it might not be backed by real parallel port hardware. Change the initialization order in the driver's comedi "attach" handler (parportattach()) so that the hardware registers are initialized before the interrupt handler is requested. This should prevent premature interrupts occurring for real hardware. Also add a test to the interrupt handler to ensure the comedi device is fully attached and return early if it isn't.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 5.15.0-198.208 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 5.15.0-1117.124 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1067.70+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1071.79+fips1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-38.38 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1008.9 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Compensating control
In the comedi_parport driver's parport_attach() handler, initialize the hardware registers before requesting the interrupt handler.
- Compensating control
Add an interrupt-handler check that verifies the comedi device is fully attached and returns early if it is not.
Event History
Frequently Asked Questions
Which systems are realistically exposed to this issue?
Systems using the Linux comedi_parport driver and its interrupt handler are relevant. The issue is associated with parallel-port hardware initialization and with user-supplied I/O port base addresses that may not correspond to real parallel-port hardware.
What conditions can trigger the fault?
A premature interrupt can occur if the interrupt handler is installed before the comedi subdevices it uses have been allocated and the parallel-port CTRL interrupt is not disabled first. It may also occur when a user-supplied I/O port base address is not backed by real hardware.
What changes address the problem?
The fix initializes the hardware registers before requesting the interrupt handler during parport_attach(). It also makes the interrupt handler return early unless the comedi device is fully attached.