CVE-2026-64270: Input: mms114 - reject an oversized device packet size

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

Input: mms114 - reject an oversized device packet size

mms114interrupt() reads a packet of touch data from the device into a fixed-size on-stack buffer

struct mms114touch touch[MMS114MAXTOUCH];

which holds MMS114MAXTOUCH (10) events of MMS114EVENTSIZE (8) bytes, i.e. 80 bytes. The length of the I2C read into it is taken verbatim from the device:

packetsize = mms114readreg(data, MMS114PACKETSIZE); if (packetsize <= 0) goto out; ... error = mms114readreg(data, MMS114INFORMATION, packetsize, (u8 )touch);

packetsize is a single device register byte (0x0F) and the only check is the lower bound packetsize <= 0; it is never bounded against the size of touch[]. A malfunctioning, malicious or counterfeit controller (or an attacker tampering with the I2C bus) can report a packetsize of up to 255, so mms114readreg() writes up to 175 bytes past the end of touch[] on the IRQ-thread stack: a stack out-of-bounds write that can overwrite the stack canary, saved registers and the return address.

A well-formed device never reports more than the buffer holds, so reject an oversized packet and drop the report, consistent with the handler's other error paths, rather than reading past the buffer.