CVE-2022-50370 — i2c: designware: Fix handling of real but unexpected device interrupts

Affected: Linux

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

i2c: designware: Fix handling of real but unexpected device interrupts

Commit c7b79a752871 ("mfd: intel-lpss: Add Intel Alder Lake PCH-S PCI IDs") caused a regression on certain Gigabyte motherboards for Intel Alder Lake-S where system crashes to NULL pointer dereference in i2c_dw_xfer_msg() when system resumes from S3 sleep state ("deep").

I was able to debug the issue on Gigabyte Z690 AORUS ELITE and made following notes:

- Issue happens when resuming from S3 but not when resuming from "s2idle" - PCI device 00:15.0 == i2c_designware.0 is already in D0 state when system enters into pci_pm_resume_noirq() while all other i2c_designware PCI devices are in D3. Devices were runtime suspended and in D3 prior entering into suspend - Interrupt comes after pci_pm_resume_noirq() when device interrupts are re-enabled - According to register dump the interrupt really comes from the i2c_designware.0. Controller is enabled, I2C target address register points to a one detectable I2C device address 0x60 and the DW_IC_RAW_INTR_STAT register START_DET, STOP_DET, ACTIVITY and TX_EMPTY bits are set indicating completed I2C transaction.

My guess is that the firmware uses this controller to communicate with an on-board I2C device during resume but does not disable the controller before giving control to an operating system.

I was told the UEFI update fixes this but never the less it revealed the driver is…

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CVE-2022-50370 — i2c: designware: Fix handling of real but unexpected device interrupts