From mboxrd@z Thu Jan 1 00:00:00 1970 From: AL-KERNEL To: kernel-cve@kernelcve.org Subject: [CVE-2026-52948][LOW] i2c: dev: prevent integer overflow in I2C_TIMEOUT ioctl Date: Fri, 26 Jun 2026 10:57:41 -0400 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-AL-KERNEL-CVE: CVE-2026-52948 X-AL-KERNEL-Priority: LOW X-AL-KERNEL-Severity: LOW X-AL-KERNEL-Base-Severity: LOW X-AL-KERNEL-KPANIC: NO X-AL-KERNEL-ActionableScore: 2 X-AL-KERNEL-ActionableScore-Lower: unknown X-AL-KERNEL-Commit: e9ffd5f5050fbb199d270a85614cd27ebed6fbac List-Id: 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. ====================================================================== 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. ====================================================================== AL-KERNEL CLASSIFICATION RESULT ====================================================================== 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 ====================================================================== ACTIONABLESCORE ANALYSIS ====================================================================== 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. ====================================================================== 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 Signed-off-by: Greg Kroah-Hartman 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).