CVE-2024-39486

Source
https://nvd.nist.gov/vuln/detail/CVE-2024-39486
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-39486.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2024-39486
Related
Published
2024-07-06T10:15:03Z
Modified
2024-09-18T03:26:29.783477Z
Severity
  • 7.0 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
Summary
[none]
Details

In the Linux kernel, the following vulnerability has been resolved:

drm/drm_file: Fix pid refcounting race

maarten.lankhorst@linux.intel.com, Maxime Ripard mripard@kernel.org, Thomas Zimmermann tzimmermann@suse.de

filp->pid is supposed to be a refcounted pointer; however, before this patch, drmfileupdatepid() only increments the refcount of a struct pid after storing a pointer to it in filp->pid and dropping the dev->filelistmutex, making the following race possible:

process A process B ========= ========= begin drmfileupdatepid mutexlock(&dev->filelistmutex) rcureplacepointer(filp->pid, <pid B>, 1) mutexunlock(&dev->filelistmutex) begin drmfileupdatepid mutexlock(&dev->filelistmutex) rcureplacepointer(filp->pid, <pid A>, 1) mutexunlock(&dev->filelistmutex) getpid(<pid A>) synchronizercu() putpid(<pid B>) * pid B reaches refcount 0 and is freed here * getpid(<pid B>) * UAF * synchronizercu() putpid(<pid A>)

As far as I know, this race can only occur with CONFIGPREEMPTRCU=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 synchronizercu() operation while process B is between mutexunlock() 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.

References

Affected packages

Debian:13 / linux

Package

Name
linux
Purl
pkg:deb/debian/linux?arch=source

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
6.9.8-1

Affected versions

6.*

6.1.27-1
6.1.37-1
6.1.38-1
6.1.38-2~bpo11+1
6.1.38-2
6.1.38-3
6.1.38-4~bpo11+1
6.1.38-4
6.1.52-1
6.1.55-1~bpo11+1
6.1.55-1
6.1.64-1
6.1.66-1
6.1.67-1
6.1.69-1~bpo11+1
6.1.69-1
6.1.76-1~bpo11+1
6.1.76-1
6.1.82-1
6.1.85-1
6.1.90-1~bpo11+1
6.1.90-1
6.1.94-1~bpo11+1
6.1.94-1
6.1.98-1
6.1.99-1
6.1.106-1
6.1.106-2
6.1.106-3
6.3.1-1~exp1
6.3.2-1~exp1
6.3.4-1~exp1
6.3.5-1~exp1
6.3.7-1~bpo12+1
6.3.7-1
6.3.11-1
6.4~rc6-1~exp1
6.4~rc7-1~exp1
6.4.1-1~exp1
6.4.4-1~bpo12+1
6.4.4-1
6.4.4-2
6.4.4-3~bpo12+1
6.4.4-3
6.4.11-1
6.4.13-1
6.5~rc4-1~exp1
6.5~rc6-1~exp1
6.5~rc7-1~exp1
6.5.1-1~exp1
6.5.3-1~bpo12+1
6.5.3-1
6.5.6-1
6.5.8-1
6.5.10-1~bpo12+1
6.5.10-1
6.5.13-1
6.6.3-1~exp1
6.6.4-1~exp1
6.6.7-1~exp1
6.6.8-1
6.6.9-1
6.6.11-1
6.6.13-1~bpo12+1
6.6.13-1
6.6.15-1
6.6.15-2
6.7-1~exp1
6.7.1-1~exp1
6.7.4-1~exp1
6.7.7-1
6.7.9-1
6.7.9-2
6.7.12-1~bpo12+1
6.7.12-1
6.8.9-1
6.8.11-1
6.8.12-1~bpo12+1
6.8.12-1
6.9.2-1~exp1
6.9.7-1~bpo12+1
6.9.7-1

Ecosystem specific

{
    "urgency": "not yet assigned"
}