iio: health: max30102: fix NULL dereference in interrupt handler

Overview

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

iio: health: max30102: fix NULL dereference in interrupt handler

The interrupt is requested in max30102_probe() and stays enabled for the lifetime of the device, but indio_dev->active_scan_mask is only valid while a buffer is enabled. When an interrupt arrives while no buffer is enabled, the handler dereferences the NULL active_scan_mask:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 Call trace: __bitmap_weight+0x64/0x98 (P) max30102_interrupt_handler+0x48/0x160 [max30102]

Call max30102_fifo_count() at the top of the handler and return early unless it reports a FIFO sample is ready. Because FIFO_RDY is the only interrupt source enabled in max30102_chip_init(), an invocation of max30102_interrupt_handler() without the FIFO_RDY interrupt status bit set carries no data to read and can return before touching active_scan_mask. A negative return from max30102_fifo_count() indicates a failed interrupt status read and is treated the same way.

Affected

• Linux >= 90579b69e94bf11ea0745ff003e82a6ce9725f96 < eeb23ba97bd8016e815ef70300b8d34a0a316b90
• Linux >= 90579b69e94bf11ea0745ff003e82a6ce9725f96 < 60699102827fdb51f9591414165359c8e867f302
• Linux >= 90579b69e94bf11ea0745ff003e82a6ce9725f96 < 8d6f98972fe2bd6f73f39d982af0c85d766a1503
• Linux >= 90579b69e94bf11ea0745ff003e82a6ce9725f96 < f0ea4824deebf21dacfbe397c4b0a5fd3e745a8d
• Linux 4.16

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.