Description

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

pinctrl: ocelot: fix system hang on level based interrupts

The current implementation only calls chained_irq_enter() and
chained_irq_exit() if it detects pending interrupts.

```
for (i = 0; i < info->stride; i++) {
uregmap_read(info->map, id_reg + 4 * i, ®);
if (!reg)
continue;

chained_irq_enter(parent_chip, desc);
```

However, in case of GPIO pin configured in level mode and the parent
controller configured in edge mode, GPIO interrupt might be lowered by the
hardware. In the result, if the interrupt is short enough, the parent
interrupt is still pending while the GPIO interrupt is cleared;
chained_irq_enter() never gets called and the system hangs trying to
service the parent interrupt.

Moving chained_irq_enter() and chained_irq_exit() outside the for loop
ensures that they are called even when GPIO interrupt is lowered by the
hardware.

The similar code with chained_irq_enter() / chained_irq_exit() functions
wrapping interrupt checking loop may be found in many other drivers:
```
grep -r -A 10 chained_irq_enter drivers/pinctrl
```

Classification

CVE ID: CVE-2024-50196

CVSS Base Severity: LOW

CVSS Base Score: 0.0

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 5.06% (scored less or equal to compared to others)

EPSS Date: 2025-02-03 (when was this score calculated)

References

https://git.kernel.org/stable/c/655f5d4662b958122b260be05aa6dfdf8768efe6
https://git.kernel.org/stable/c/4a81800ef05bea5a9896f199677f7b7f5020776a
https://git.kernel.org/stable/c/20728e86289ab463b99b7ab4425515bd26aba417
https://git.kernel.org/stable/c/dcbe9954634807ec54e22bde278b5b269f921381
https://git.kernel.org/stable/c/93b8ddc54507a227087c60a0013ed833b6ae7d3c

Timeline