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CVE-2024-39486 Design/Logic Flaw

Remediate Within 6 Months

CVE Information

Original CVE data


In the Linux kernel, the following vulnerability has been resolved: drm/drm_file: Fix pid refcounting race filp->pid is supposed to be a refcounted pointer; however, before this patch, drm_file_update_pid() only increments the refcount of a struct pid after storing a pointer to it in filp->pid and dropping the dev->filelist_mutex, making the following race possible: process A process B ========= ========= begin drm_file_update_pid mutex_lock(&dev->filelist_mutex) rcu_replace_pointer(filp->pid, <pid B>, 1) mutex_unlock(&dev->filelist_mutex) begin drm_file_update_pid mutex_lock(&dev->filelist_mutex) rcu_replace_pointer(filp->pid, <pid A>, 1) mutex_unlock(&dev->filelist_mutex) get_pid(<pid A>) synchronize_rcu() put_pid(<pid B>) *** pid B reaches refcount 0 and is freed here *** get_pid(<pid B>) *** UAF *** synchronize_rcu() put_pid(<pid A>) As far as I know, this race can only occur with CONFIG_PREEMPT_RCU=y because it requires RCU to detect a quiescent state in code that is not explicitly calling into the scheduler. This race leads to use-after-free of a "struct pid". It is probably somewhat hard to hit because process A has to pass through a synchronize_rcu() operation while process B is between mutex_unlock() and get_pid(). Fix it by ensuring that by the time a pointer to the current task's pid is stored in the file, an extra reference to the pid has been taken. This fix also removes the condition for synchronize_rcu(); I think that optimization is unnecessary complexity, since in that case we would usually have bailed out on the lockless check above.

CVSS v2-
CVSS v3-
Affected Vendors

Basic Analysis

Common vulnerability metrics

Vulnerabilty type as detected by PRIOnengine

Design/Logic Flaw

CVSS Scores as calculated by PRIOnengine
CVSS v24.3
CVSS v37



No exploit code is reported to exist.

Active Exploitation

Vulnerability is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. See the KEV Catalog

Social Network Activity


Threat Actor Activity

No sightings of the vulnerability within threat reports.

Cybersecurity Frameworks

How the vulnerability maps against various cybersecurity frameworks

T1499.004 - Endpoint Denial of Service (Application or System Exploitation)
T1203 - Exploitation for Client Execution
T1059 - Command and Scripting Interpreter

Compliance Impact

How the submited vulnerability affects compliance

PCI DSS v3.2.1-6.5.2 - Buffer Overflows

Web Application Security Frameworks

Applicable if the issue likely affects a web application

WASC-8 - Cross Site Scripting