Input: iforce - bound the device-reported force-feedback effect index

Summary

In the Linux kernel, the following vulnerability has been resolved: Input: iforce - bound the device-reported force-feedback effect index iforce_process_packet() handles a status report (packet id 0x02) by taking a force-feedback effect index straight from the device wire and using it to address the per-effect state array: i = data[1] & 0x7f; if (data[1] & 0x80) { if (!test_and_set_bit(FF_CORE_IS_PLAYED, iforce->core_effects[i].flags)) ... } else if (test_and_clear_bit(FF_CORE_IS_PLAYED, iforce->core_effects[i].flags)) { ... } The index is masked only with 0x7f, so it ranges 0..127, but core_effects[] holds only IFORCE_EFFECTS_MAX (32) entries. For an index of 32..127 the test_and_set_bit()/test_and_clear_bit() is an out-of-bounds single-bit read-modify-write past the array. core_effects[] is the second-to-last member of struct iforce, so the write lands in the trailing members and beyond the embedding kzalloc()'d iforce_serio / iforce_usb object. data[1] is unvalidated device payload on both transports (the USB interrupt endpoint and serio), and the status path is not gated on force feedback being present, so a malicious or counterfeit device can set or clear a bit at an attacker-chosen offset past the object. Reject an out-of-range index instead of indexing with it. Bound against the array dimension IFORCE_EFFECTS_MAX rather than dev->ff->max_effects so the check guarantees memory safety regardless of how many effects the device registered. A legitimate "effect started/stopped" status always carries an index below IFORCE_EFFECTS_MAX, so well-formed devices are unaffected; the neighbouring mark_core_as_ready() loop is already bounded and is left untouched.