CVE-2026-46022

Summary

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

misc: ibmasm: fix OOB MMIO read in ibmasm_handle_mouse_interrupt()

ibmasm_handle_mouse_interrupt() performs an out-of-bounds MMIO read when the queue reader or writer index from hardware exceeds REMOTE_QUEUE_SIZE (60).

A compromised service processor can trigger this by writing an out-of-range value to the reader or writer MMIO register before asserting an interrupt. Since writer is re-read from hardware on every loop iteration, it can also be set to an out-of-range value after the loop has already started.

The root cause is that get_queue_reader() and get_queue_writer() return raw readl() values that are passed directly into get_queue_entry(), which computes:

queue_begin + reader * sizeof(struct remote_input)

with no bounds check. This unchecked MMIO address is then passed to memcpy_fromio(), reading 8 bytes from unintended device registers. For sufficiently large values the address falls outside the PCI BAR mapping entirely, triggering a machine check exception.

Fix by checking both indices against REMOTE_QUEUE_SIZE at the top of the loop body, before any call to get_queue_entry(). On an out-of-range value, reset the reader register to 0 via set_queue_reader() before breaking, so that normal queue operation can resume if the corrupted hardware state is transient.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/6f6ecc9153df176e956d0664b56f93080b0a45f0
• https://git.kernel.org/stable/c/bac8643486f854dd53af9b23aea7dbbd9b7c1865
• https://git.kernel.org/stable/c/f7e5b4eefd7be3e09f8bd5fee63ed478fd7446ab
• https://git.kernel.org/stable/c/fc7e9a74e32299d7e93e178ca482a0b59ef1595b
• https://git.kernel.org/stable/c/07c4f18b303106e6b24492c12b95d48a4b985841
• https://git.kernel.org/stable/c/22a16d3eafee92a165c756081587c95850127107
• https://git.kernel.org/stable/c/1ca75f6b74ec7f685464e5745ecfcf3a76d284e9
• https://git.kernel.org/stable/c/4b6e6ead556734bdc14024c5f837132b1e7a4b84

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