CVE-2024-41088

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

can: mcp251xfd: fix infinite loop when xmit fails

When the mcp251xfdstartxmit() function fails, the driver stops processing messages, and the interrupt routine does not return, running indefinitely even after killing the running application.

Error messages: [ 441.298819] mcp251xfd spi2.0 can0: ERROR in mcp251xfdstartxmit: -16 [ 441.306498] mcp251xfd spi2.0 can0: Transmit Event FIFO buffer not empty. (seq=0x000017c7, teftail=0x000017cf, tefhead=0x000017d0, tx_head=0x000017d3). ... and repeat forever.

The issue can be triggered when multiple devices share the same SPI interface. And there is concurrent access to the bus.

The problem occurs because txring->head increments even if mcp251xfdstartxmit() fails. Consequently, the driver skips one TX package while still expecting a response in mcp251xfdhandletefifone().

Resolve the issue by starting a workqueue to write the tx obj synchronously if err = -EBUSY. In case of another error, decrement tx_ring->head, remove skb from the echo stack, and drop the message.

[mkl: use more imperative wording in patch description]