UBUNTU-CVE-2026-89622: Use After Free

In the Linux kernel, the following vulnerability has been resolved: HID: mcp2221: clear rxbuf after I2C/SMBus transfer completes mcpi2csmbusread() stores the caller-supplied buffer pointer in mcp->rxbuf for the duration of a transfer but never clears it when the transfer finishes or times out. Once the caller frees or reuses the buffer, mcp->rxbuf becomes a dangling pointer. A delayed or spurious MCP2221I2CGETDATA report can then drive mcp2221rawevent() to memcpy device data into the freed memory, causing a write use-after-free. Route all return paths through a single exit point that clears mcp->rxbuf and mcp->rxbufsize, so that the existing !mcp->rxbuf guard in the rawevent handler can reject any report arriving after the transfer has ended.