CVE-2021-47050

What it actually does

The vulnerability is a NULL pointer dereference in the renesas-rpc-if memory driver caused by calling resource_size() on the unchecked return value of platform_get_resource_byname().

Why it matters to the business

Affected Linux systems using Renesas RPC-IF hardware may suffer kernel panics or reboots, interrupting memory-related operations and reducing system availability.

How an attack unfolds

An attacker triggers the driver code path on a system with the renesas-rpc-if platform device where the named resource lookup fails, causing the subsequent unconditional dereference to crash the kernel.

How to fix it

Update the Linux kernel to a version containing the fix that validates the resource pointer before calling resource_size().

How to confirm the fix worked

Inspect drivers/memory/renesas-rpc-if.c for the added NULL check after platform_get_resource_byname(), or verify the patched kernel version is running on affected hardware.

Typical attack path

1. Gain local access or ability to load the renesas-rpc-if driver
2. Arrange for platform_get_resource_byname() to return NULL for the expected resource name
3. Execute code that reaches the resource_size() call without a prior NULL check
4. Trigger kernel panic from the NULL dereference

How to detect it

Search kernel logs and crash dumps for oops or panic messages referencing renesas-rpc-if, platform_get_resource_byname, or resource_size near a NULL dereference.

• renesas-rpc-if
• platform_get_resource_byname
• resource_size
• NULL pointer dereference

What your security team should do

• Prioritize kernel updates on systems that include the renesas-rpc-if driver
• Review boot logs and dmesg for any prior NULL dereference reports involving the driver
• Disable the driver module if the hardware is not required