HID: nintendo: fix out-of-bounds read in joycon_ctlr_read_handler()

Overview

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

HID: nintendo: fix out-of-bounds read in joycon_ctlr_read_handler()

joycon_ctlr_read_handler() casts an incoming HID input report to struct joycon_input_report and parses it, guarding the cast only with a 12-byte length check:

if (size >= 12) /* make sure it contains the input report */
	joycon_parse_report(ctlr, (struct joycon_input_report *)data);

struct joycon_input_report is 49 bytes: a 13-byte header followed by a union whose IMU arm is 36 bytes. For an IMU report joycon_parse_report() -> joycon_parse_imu_report() walks that union (struct offsets 13..48), so a report of exactly 12 bytes with data[0] == JC_INPUT_IMU_DATA passes the guard yet is read up to 37 bytes past its declared length. The over-read bytes are decoded into accelerometer/gyroscope values and forwarded to userspace through the "(IMU)" input device, leaking driver-internal memory. data[0] and size are fully controlled by a malicious or spoofed Joy-Con/Pro Controller.

Receive buffers are sized to the maximum report length, so this is an over-read within the allocation rather than a slab OOB, but the decoded bytes still reach userspace.

The sibling subcmd path in joycon_ctlr_handle_event() already bounds the same cast correctly:

if (size < sizeof(struct joycon_input_report) ||
    data[0] != JC_INPUT_SUBCMD_REPLY)
	break;

Use the same sizeof(struct joycon_input_report) bound here.

Affected

• Linux >= 2af16c1f846bd60240745bbd3afa13d5f040c61a < 33ea29f8b6141f2d265de807e110a6435b355cb0
• Linux >= 2af16c1f846bd60240745bbd3afa13d5f040c61a < bd397c4123a4bc084913d8c7fdb40ef94e9f8172
• Linux >= 2af16c1f846bd60240745bbd3afa13d5f040c61a < addca61f9a23c0d20a387c2040e70479f54518e1
• Linux >= 2af16c1f846bd60240745bbd3afa13d5f040c61a < 51cfd1adbe7a46bb08af162abb3ab3b6820e2d15
• Linux >= 2af16c1f846bd60240745bbd3afa13d5f040c61a < d4cabd4089adb59cf7974915737c52cc47a9bb1b
• Linux >= 2af16c1f846bd60240745bbd3afa13d5f040c61a < 34725ed4719da424113db8449fb5485aaf71a913
• Linux >= 2af16c1f846bd60240745bbd3afa13d5f040c61a < 27b376b945c0aac46fcdfcc950b14a85b874b557
• Linux 5.16

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.