From: AL-KERNEL <[email protected]>
To: [email protected]
Subject: [CVE-2026-52966][MODERATE REGULAR] drm: Replace old pointer to new idr
Date: Thu, 25 Jun 2026 10:09:47 -0400 [thread overview]
Message-ID: <[email protected]> (raw)
CVE: CVE-2026-52966
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm: Replace old pointer to new idr
Commit: 318b995cffcfcaa69a234d28123a3f4ae186a9df
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=318b995cffcfcaa69a234d28123a3f4ae186a9df
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52966
Analysis date: Thu, 25 Jun 2026 10:09:47 -0400
ActionableScore: 3
ActionableScore lower bound: 2
Actionable bucket: Ordinary Moderate / Low-like. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED
Manual review required: YES
Summary:
A local DRM user can trigger inconsistent GEM PRIME dma_buf bookkeeping through the change_handle ioctl path, leading to a cleanup WARN and possible local DoS or resource leakage, but the patch does not show a concrete memory corruption or privilege escalation primitive.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-52966 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52966
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: MODERATE REGULAR
Manual review required: YES
A detailed explanation of the methodology and priority rules is included
at the end of this message.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-52966 MODERATE 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-664;*CWE-772;CWE-404;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'DRM GEM change_handle can leave per file PRIME dma_buf bookkeeping inconsistent because the IDR pointer replacement is performed at the wrong point in the handle change flow. A local process with access to a DRM device node can exercise the ioctl path and trigger a warning during drm_file cleanup when prime_fpriv dmabufs is still non empty. For the CVSS the PR:L is used because triggering requires local access to a DRM file descriptor or render node, but not full administrator privileges on common desktop or GPU compute systems. The issue is not network reachable. Impact is mainly denial of service or resource leakage, with high availability only in configurations where WARN can panic the kernel or repeated abuse can exhaust resources.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED (with actual score 3) SKIP CVE-2026-52966 SKIP The Fixes patch not applied yet, so unlikely that actual: 5e28b7b94408897e41c63477aabc9e1db439bc8c YES NO NO unknown MAYBE WARNONLY HARDWARE LINUS SYZBOT INCREASED_FROM_LOW_BASED_ON_HIGHCVSSSCORE DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5 - - checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=3
ActionableScoreLower=2
## 1. ActionableScore
* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Ordinary Moderate / Low-like. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED**
## 2. Signal breakdown
Conservative signals:
* Local unprivileged trigger: +1
A local process with access to a DRM device node or render node can potentially reach `drm_gem_change_handle_ioctl()`.
* Availability impact realistic: +1
The demonstrated effect is a WARN during DRM file cleanup due to inconsistent PRIME dma_buf bookkeeping. This may be DoS relevant mainly with `panic_on_warn` or repeated resource leakage.
Paranoid additional signal:
* Broad/common subsystem exposure: +1
DRM render nodes are common on desktop, workstation, and GPU compute systems and are often accessible to non-root local users.
Signals not applied:
* No generic memory corruption: 0
The patch shows an IDR bookkeeping error, not UAF, OOB write, double free, or attacker-controlled overwrite.
* No privilege escalation plausible: 0
No concrete primitive for credential overwrite, object reclaim, arbitrary write, or sensitive data access is shown.
* No remote reachability: 0
This is an ioctl/control path, not a network-triggerable path.
* No admin penalty: 0
Full root is not typically required if `/dev/dri/renderD*` is accessible.
## 3. Reachability analysis
The bug is locally reachable through DRM GEM handle management, assuming the attacker can open a DRM device node. On many desktop and GPU compute deployments, render nodes are available to ordinary users via group or logind permissions, so PR:L is the realistic CVSS-style interpretation. Containers only matter if a DRM device is passed through, but that still makes the trigger local to the container workload rather than network reachable. The path is not universally enabled on headless servers without exposed GPU devices.
## 4. Severity interpretation
This behaves like an ordinary Moderate or Low-like kernel issue, not an Important-class vulnerability. The realistic impact is a local WARN-based DoS or resource bookkeeping leak. Theoretical escalation is not supported by the patch because there is no shown UAF reclaim, arbitrary write, page-cache corruption, or controlled object confusion. The paranoid score only accounts for common DRM exposure and possible stronger availability impact under `panic_on_warn`.
## 5. One-sentence report phrase
A local DRM user can trigger inconsistent GEM PRIME dma_buf bookkeeping through the change_handle ioctl path, leading to a cleanup WARN and possible local DoS or resource leakage, but the patch does not show a concrete memory corruption or privilege escalation primitive.
## 6. Manual review recommendation
NO MANUAL CHECK NEEDED.
The issue is suitable for deferred or automatic handling because the evidence points to local bookkeeping inconsistency and WARN/resource-leak impact without a supported memory corruption, information disclosure, or privilege escalation primitive.
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: drm: Replace old pointer to new idr
Commit: 318b995cffcfcaa69a234d28123a3f4ae186a9df
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=318b995cffcfcaa69a234d28123a3f4ae186a9df
Commit description:
Commit 5e28b7b introduced a logical error by failing to replace the
newly generated IDR pointer to old id's pointer at the correct location
within the "change handle" logic; this resulted in the issue reported by
syzbot [1].
Specifically, the new IDR object pointer is intended to replace the original
id's pointer during the normal execution flow.
Additionally, an unnecessary conditional check for the ret exit path has
been removed.
[1]
!RB_EMPTY_ROOT(&prime_fpriv->dmabufs)
WARNING: drivers/gpu/drm/drm_prime.c:224 at drm_prime_destroy_file_private+0x48/0x60 drivers/gpu/drm/drm_prime.c:224, CPU#0: syz.0.17/5833
Call Trace:
drm_file_free.part.0+0x7e6/0xcc0 drivers/gpu/drm/drm_file.c:269
drm_file_free drivers/gpu/drm/drm_file.c:237 [inline]
drm_close_helper.isra.0+0x186/0x200 drivers/gpu/drm/drm_file.c:290
drm_release+0x1ab/0x360 drivers/gpu/drm/drm_file.c:438
Fixes: 5e28b7b ("drm: Set old handle to NULL before prime swap in change_handle")
Reported-by: [email protected]
Closes: https://syzkaller.appspot.com/bug?extid=d7c9eed171647e421013
Cc: [email protected]
Tested-by: [email protected]
Signed-off-by: Edward Adam Davis <[email protected]>
Signed-off-by: Dave Airlie <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Changed files:
drivers/gpu/drm/drm_prime.c
drivers/gpu/drm/drm_file.c
drivers/gpu/drm/drm_gem.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=318b995cffcfcaa69a234d28123a3f4ae186a9df
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-52966 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-52966
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: 2
Paranoid ActionableScore: 3
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: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR
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 [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
reply other threads:[~2026-06-25 14:09 UTC|newest]
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