Bug 2516716 (CVE-2026-72141)

Summary: CVE-2026-72141 kernel: i2c: imx: fix locked bus on SMBus block-read of 0 (IRQ)
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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OS: Linux   
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A flaw was found in the Linux kernel's i2c-imx driver. A malicious device on the I2C bus or a local attacker with access to the I2C bus could exploit this vulnerability by initiating an SMBus block-read operation with a zero byte count. This can cause the I2C bus to become locked, requiring a power cycle of the controller to restore functionality, leading to a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-08-15 06:27:22 UTC 
In the Linux kernel, the following vulnerability has been resolved:

i2c: imx: fix locked bus on SMBus block-read of 0 (IRQ)

SMBus 3.1 6.5.7 allows a Block Read byte count of 0, but the
interrupt-driven block-read state machine rejects it as -EPROTO. Worse,
it returns without a NACK+STOP: the next receive cycle has already
started, so the target keeps holding SDA and the bus stays stuck until a
power cycle of this i2c controller.

Accept count=0: NACK the in-flight dummy byte (TXAK) and set msg->len to
2 so i2c_imx_isr_read_continue() emits STOP via its normal last-byte
path. The dummy byte is discarded; block-read callers only consume
buf[0..count-1].

Reading I2DR has likewise already armed the next byte on the
count > I2C_SMBUS_BLOCK_MAX error path, so NACK it (TXAK) before aborting
with -EPROTO; otherwise the failing transfer's STOP cannot complete and
the bus stays held.

The atomic path regressed earlier (v3.16) and is fixed separately; this
patch covers only the v6.13 state-machine rework.
Comment 1 Keith Grant 2026-08-18 12:17:31 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081532-CVE-2026-72141-2eec@gregkh/T