Bug 2393504 (CVE-2025-39685)

Summary: CVE-2025-39685 kernel: comedi: pcl726: Prevent invalid irq number
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Description OSIDB Bzimport 2025-09-05 18:02:51 UTC 
In the Linux kernel, the following vulnerability has been resolved:

comedi: pcl726: Prevent invalid irq number

The reproducer passed in an irq number(0x80008000) that was too large,
which triggered the oob.

Added an interrupt number check to prevent users from passing in an irq
number that was too large.

If `it->options[1]` is 31, then `1 << it->options[1]` is still invalid
because it shifts a 1-bit into the sign bit (which is UB in C).
Possible solutions include reducing the upper bound on the
`it->options[1]` value to 30 or lower, or using `1U << it->options[1]`.

The old code would just not attempt to request the IRQ if the
`options[1]` value were invalid.  And it would still configure the
device without interrupts even if the call to `request_irq` returned an
error.  So it would be better to combine this test with the test below.
Comment 1 Jon Moroney 2025-09-05 21:44:47 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025090546-CVE-2025-39685-ddff@gregkh/T