[CVE-2026-52948][LOW] i2c: dev: prevent integer overflow in I2C_TIMEOUT ioctl

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-52948
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: i2c: dev: prevent integer overflow in I2C_TIMEOUT ioctl
Commit: e9ffd5f5050fbb199d270a85614cd27ebed6fbac
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e9ffd5f5050fbb199d270a85614cd27ebed6fbac
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52948
Analysis date: Fri, 26 Jun 2026 10:57:41 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
An integer overflow in the `I2C_TIMEOUT` ioctl allows a local user with access to an I2C device node to set an invalid negative adapter timeout, potentially leaving the SMBus controller state machine unrecoverable and causing local DoS.

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ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-52948 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52948

The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.

The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.

Published priority for this report: LOW
Manual review required: NO

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-52948	LOW	CHECK	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H';CWE-190;*CWE-20;CWE-754;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'An integer overflow in the I2C_TIMEOUT ioctl can let a local user set an excessive timeout value in 10 ms units that overflows when multiplied by 10 before conversion to jiffies. The truncated value can be stored as a negative adapter timeout and later sign extended in wait_for_completion_timeout, causing schedule_timeout warnings and premature timeout handling. This can leave the SMBus controller state machine in an unrecoverable state and cause a local denial of service for the affected adapter. For the CVSS the PR:L is used because an attacker needs local access to an i2c device node or an equivalent process context able to issue the ioctl. The issue is not network reachable. Impact is denial of service only, with no supported memory corruption, information disclosure, or privilege escalation primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2) 	MAYBE	USB WARNONLY LINUS  INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Ordinary Moderate / Low-like**

## 2. Signal breakdown

Conservative scoring:

* Local trigger through device ioctl: +1
  A local process with access to `/dev/i2c-*` can issue `I2C_TIMEOUT`.

* Reliable local DoS against affected I2C/SMBus adapter: +1
  The overflow can create an invalid negative timeout and leave the SMBus controller state machine unrecoverable.

* No memory corruption signal: +0
  The issue is integer overflow and bad timeout propagation, not UAF, OOB write, double free, arbitrary write, or object lifetime corruption.

* No privilege escalation signal: +0
  The patch and described behavior support local DoS only.

* No remote reachability: +0
  This is an ioctl path, not network-triggerable.

* Configuration and access constraints: -0 to -1
  `i2c-dev` and accessible `/dev/i2c-*` nodes are not universally exposed to unprivileged users. I do not subtract in the main score because access is common on some embedded or hardware-management systems.

Paranoid score adds:

* Persistent availability impact: +1
  If the SMBus controller remains stuck until reset or reboot, the availability impact may be more operationally significant.

## 3. Reachability analysis

The bug is reachable by a local process that can open an I2C device node and issue the `I2C_TIMEOUT` ioctl. In typical general-purpose deployments, `/dev/i2c-*` access is often restricted to root or a hardware-access group, but embedded systems, test systems, and device-management services may expose it to less privileged local users. Containers do not normally get I2C device nodes unless explicitly passed through, so namespaces usually reduce exposure rather than increase it. The path is not network reachable and does not involve a common packet-processing or remote protocol parser.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like kernel issue, not an Important-class vulnerability. The demonstrated impact is local denial of service of the affected I2C/SMBus controller through invalid timeout handling. There is no supported evidence of kernel memory corruption, information disclosure, arbitrary write, object lifetime corruption, or privilege escalation. The paranoid view can treat the DoS as operationally stronger if the controller state remains unrecoverable, but it still remains DoS-only.

## 5. One-sentence report phrase

An integer overflow in the `I2C_TIMEOUT` ioctl allows a local user with access to an I2C device node to set an invalid negative adapter timeout, potentially leaving the SMBus controller state machine unrecoverable and causing local DoS.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: this is a local ioctl-triggered integer overflow with DoS-only impact and no demonstrated memory corruption or privilege escalation primitive.

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UPSTREAM PATCH SUMMARY
======================================================================

Patch: i2c: dev: prevent integer overflow in I2C_TIMEOUT ioctl
Commit: e9ffd5f5050fbb199d270a85614cd27ebed6fbac
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e9ffd5f5050fbb199d270a85614cd27ebed6fbac

Commit description:

While fuzzing with Syzkaller, a persistent `schedule_timeout: wrong
timeout value` warning was observed, accompanied by SMBus controller
state machine corruption.

The I2C_TIMEOUT ioctl accepts a user-provided timeout in multiples of
10 ms. The user argument is checked against INT_MAX, but it is
subsequently multiplied by 10 before being passed to msecs_to_jiffies().

A malicious user can pass a large value (e.g., 429496729) that passes
the `arg > INT_MAX` check but overflows when multiplied by 10. This
results in a truncated 32-bit unsigned value that bypasses the
internal `(int)m < 0` check in `msecs_to_jiffies()`.

The truncated value is then assigned to `client->adapter->timeout`
(a signed 32-bit int), which is reinterpreted as a negative number.
When passed to wait_for_completion_timeout(), this negative value
undergoes sign extension to a 64-bit unsigned long, triggering the
`schedule_timeout` warning and causing premature returns. This leaves
the SMBus state machine in an unrecoverable state, constituting a
local Denial of Service (DoS).

Fix this by bounding the user argument to `INT_MAX / 10`.

Signed-off-by: Mingyu Wang <25181214217@stu.xidian.edu.cn>
[wsa: move the comment as well]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/i2c/i2c-dev.c

Diff excerpt:

Not included in this email. See the upstream URL for the full patch.

Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e9ffd5f5050fbb199d270a85614cd27ebed6fbac

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-52948 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52948

The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.

The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.

The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.

Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:

  Conservative CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 5.5

The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.

CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.

A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.

  Conservative ActionableScore: unknown
  Paranoid ActionableScore: 2

The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.

For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:

  ActionableScore below 5   -> MODERATE REGULAR
  ActionableScore 5 or more -> MODERATE 7.0

The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.

There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).

KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.

AL-KERNEL base severity for this report: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).

Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).