CVE-2026-89628

Summary

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

HID: picolcd: clamp eeprom debugfs read to bytes actually received

picolcd_debug_eeprom_read() trusts resp->raw_data[2] – a length byte supplied by the device in its REPORT_EE_DATA reply – clamped only to the caller's read() count:

ret = resp->raw_data[2];
if (ret > s)
	ret = s;
if (copy_to_user(u, resp->raw_data+3, ret))

It never checks resp->raw_size, the number of bytes picolcd_raw_event() actually copied into the 64-byte raw_data[] of the kmalloc'd struct picolcd_pending. A device (or a spoofed picoLCD) returning a length byte of 0xff, read with a count >= 255, makes copy_to_user() read past raw_data[] into adjacent slab memory and return it to userspace through the debugfs "eeprom" file:

BUG: KASAN: slab-out-of-bounds in _copy_to_user
Read of size 255 ... picolcd_debug_eeprom_read+0x214/0x2f0 [hid_picolcd]

The debug-dump path in the same file already validates the device length byte against the received size before trusting it; this read does not. The file is created S_IRUSR (root-only) and a crafted device is needed, so it is neither unprivileged- nor remotely-triggerable.

Clamp the copy length to resp->raw_size - 3 (the payload actually received, minus the 3-byte header), floored at 0 for short replies.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/a3e6e8d7198a9f3861861520a38b673684a1062b
• https://git.kernel.org/stable/c/471f4a939c66d1d44aece2321807abf609fc9098
• https://git.kernel.org/stable/c/699a3c8b56e168ca19d12722f3f5ef1d6f4b1d84
• https://git.kernel.org/stable/c/e9c667395ac1f8024f623250b32bae4c7af9caa0

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