Bug 2536224 (CVE-2026-90070)

Summary: CVE-2026-90070 kernel: tpm: st33zp24: Return zero on status read failure
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Trusted Platform Module (TPM) driver for the ST33ZP24 chip. The `st33zp24_status()` function does not correctly handle errors when reading data from the I2C transport. This can result in uninitialized data being interpreted as valid TPM status flags, leading to incorrect status checks and potentially causing system instability or denial of service by making callers act on invalid status values.
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Description OSIDB Bzimport 2026-09-17 16:59:34 UTC 
In the Linux kernel, the following vulnerability has been resolved:

tpm: st33zp24: Return zero on status read failure

st33zp24_status() ignores the result of the transport read and returns
data even when no byte was received. The I2C transport, for example,
skips i2c_master_recv() when the register-select write is short or fails,
leaving data uninitialized. The resulting stack value can be interpreted
as TPM_STS flags and let status checks complete spuriously.

The status callback cannot propagate a transport error. Return zero
unless recv() reports exactly one byte. With no status bits set, callers
retry or take their existing timeout or error path instead of acting on
an invalid status value.

This issue was found by a static analysis checker and confirmed by manual
source review.
Comment 1 Keith Grant 2026-09-22 17:11:09 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90070.mbox