CVE-2024-26999

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

serial/pmac_zilog: Remove flawed mitigation for rx irq flood

The mitigation was intended to stop the irq completely. That may be

better than a hard lock-up but it turns out that you get a crash anyway

if you're using pmac_zilog as a serial console:

ttyPZ0: pmz: rx irq flood !

BUG: spinlock recursion on CPU#0, swapper/0

That's because the pr_err() call in pmz_receive_chars() results in

pmz_console_write() attempting to lock a spinlock already locked in

pmz_interrupt(). With CONFIG_DEBUG_SPINLOCK=y, this produces a fatal

BUG splat. The spinlock in question is the one in struct uart_port.

Even when it's not fatal, the serial port rx function ceases to work.

Also, the iteration limit doesn't play nicely with QEMU, as can be

seen in the bug report linked below.

A web search for other reports of the error message "pmz: rx irq flood"

didn't produce anything. So I don't think this code is needed any more.

Remove it.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References