CVE-2021-47263: 
Linux Kernel vulnerability analysis and mitigation

CVE-2021-47263 is a vulnerability in the Linux kernel's GPIO WCD934x driver that was discovered and resolved in 2024. The issue involves a shift-out-of-bounds error in the bit-mask calculation for pins 0 to 4, where BIT(n - 1) was incorrectly used instead of BIT(n) (NVD, Kernel Commit).

The vulnerability exists in the drivers/gpio/gpio-wcd934x.c file at line 34, where the WCDPINMASK macro incorrectly calculated bit masks for GPIO pins. The original code used BIT(p - 1) which could result in undefined behavior when accessing pin 0, as detected by UBSAN (Undefined Behavior Sanitizer). The fix involved changing the macro to use BIT(p) instead, ensuring proper bit mask calculations for all pins from 0 to 4 (Kernel Commit).

The shift-out-of-bounds error could potentially lead to undefined behavior in the Linux kernel's GPIO subsystem when interacting with WCD934x hardware. This could affect systems using the WCD934x GPIO controller (NVD).

The vulnerability has been fixed through a patch that corrects the bit mask calculation in the WCD934x GPIO driver. The fix was committed to the Linux kernel and is available in updated kernel versions. Users should update their Linux kernel to a version that includes this fix (Kernel Commit).