CVE-2021-47409: 
Linux Kernel vulnerability analysis and mitigation

CVE-2021-47409 is a vulnerability in the Linux kernel's USB DWC2 (DesignWare USB 2.0) driver. The issue was discovered when it was found that the driver did not properly check the return value after calling platform_get_resource(), which could lead to a null pointer dereference. The vulnerability was identified and patched in 2021 (Kernel Git).

The vulnerability exists in the drivers/usb/dwc2/hcd.c file of the Linux kernel. The issue occurs when the platform_get_resource() function is called without proper return value validation. If the function returns NULL, it could lead to a null pointer dereference when attempting to access the resource. The fix involves adding a proper check for the NULL return value and returning -EINVAL error code in such cases (Kernel Git).

If exploited, this vulnerability could cause a null pointer dereference in the Linux kernel's USB subsystem, potentially leading to a system crash or denial of service condition (CVE Mitre).

The vulnerability requires local access to a system with the affected USB DWC2 driver. It can be triggered through normal USB device operations when the platform_get_resource() function returns NULL (Kernel Git).

The vulnerability has been fixed in multiple Linux kernel versions. The fix involves adding proper NULL checking after the platform_get_resource() call. Various Linux distributions have released updated kernel packages containing the fix. Debian has fixed this in versions 5.10.223-1 for bullseye, 6.1.123-1 for bookworm, and 6.12.12-1 for trixie (Debian Security).