Executive Summary

The Linux kernel DS28E17 1‑Wire to I2C bridge driver allows an attacker to supply an oversized length byte (0‑255) during an I2C_M_RECV_LEN read. The driver copies the requested length into a 34‑byte buffer without validating against I2C_SMBUS_BLOCK_MAX, causing an out‑of‑bounds read of up to ~222 bytes. This can lead to memory corruption and potential privilege escalation. The issue is mitigated by rejecting lengths above I2C_SMBUS_BLOCK_MAX at both RECV_LEN sites.

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Authoritative CVE Metadata - CVSS Base Score: 7.8 (HIGH) - Published: 2026-09-11T20:18:56.893 - Last Modified: 2026-09-13T07:17:00.787

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

w1: ds28e17: reject an oversize length on an I2C block read

w1_f19_i2c_master_transfer() is the master_xfer for the DS28E17 1-Wire to I2C bridge. On an I2C_M_RECV_LEN read, it takes the length from the device. The downstream slave puts a length byte in buf[0]. The driver then reads that many bytes into buf[1] with w1_f19_i2c_read().

buf[0] is controlled by the device and can be 0 to 255. w1_f19_i2c_read() only rejects a zero count. The caller buffer is I2C_SMBUS_BLOCK_MAX + 2, so 34 bytes. A length above 32 makes the read run past it, up to about 222 bytes out of bounds.

The SMBus core does check buf[0] against I2C_SMBUS_BLOCK_MAX. That check runs after master_xfer returns. By then the write is already done. i2c-algo-bit rejects an oversize length before it copies, and returns -EPROTO.

Reject a length above I2C_SMBUS_BLOCK_MAX at both RECV_LEN sites, the same way i2c-algo-bit does.

"There are two primary choices in life: to accept conditions as they exist, or accept responsibility for changing them."

— Denis Waitley