CVE-2025-21804: PCI: rcar-ep: Fix incorrect variable used when calling devm_request_mem_region()
In the Linux kernel, the following vulnerability has been resolved:
PCI: rcar-ep: Fix incorrect variable used when calling devm_request_mem_region()
The rcar_pcie_parse_outbound_ranges() uses the devm_request_mem_region()
macro to request a needed resource. A string variable that lives on the
stack is then used to store a dynamically computed resource name, which
is then passed on as one of the macro arguments. This can lead to
undefined behavior.
Depending on the current contents of the memory, the manifestations of
errors may vary. One possible output may be as follows:
$ cat /proc/iomem
30000000-37ffffff :
38000000-3fffffff :
Sometimes, garbage may appear after the colon.
In very rare cases, if no NULL-terminator is found in memory, the system
might crash because the string iterator will overrun which can lead to
access of unmapped memory above the stack.
Thus, fix this by replacing outbound_name with the name of the previously
requested resource. With the changes applied, the output will be as
follows:
$ cat /proc/iomem
30000000-37ffffff : memory2
38000000-3fffffff : memory3
[kwilczynski: commit log]
Security readout for executives and security teams
Plain-English summary
This Linux kernel issue affects the Renesas R-Car PCI endpoint driver. A bad resource-name pointer can cause incorrect memory-resource labeling and, rarely, a kernel crash. The public sources do not show remote attackability, privilege impact, or active exploitation.
Executive priority
Treat this as a targeted kernel reliability fix, not an internet-wide emergency. Prioritize patching for affected embedded, automotive, or appliance platforms that use R-Car PCI endpoint functionality.
Technical view
rcar_pcie_parse_outbound_ranges() passed a stack-based dynamically computed name to devm_request_mem_region(), creating undefined behavior after the stack storage was no longer valid. Kernel stable fixes replace that value with the previously requested resource name.
Likely exposure
Exposure is most likely on Linux systems using the Renesas R-Car PCI endpoint driver and affected kernel builds listed by the CVE source. General Linux servers without this hardware or driver path are less likely to be exposed.
Exploitation context
The CVE record describes incorrect /proc/iomem output and rare crash potential. KEV is false, and the provided sources do not cite active exploitation, public exploit use, or a remote attack path.
Researcher notes
Evidence is strongest for a memory-lifetime bug causing undefined behavior in resource naming. Impact details remain limited: no CVSS, CWE, exploitability analysis, or privilege boundary assessment is included in the supplied sources.
Mitigation direction
Update affected Linux kernels to vendor-supported releases containing the stable fixes.
Apply relevant Debian LTS kernel security updates where Debian packages are used.
Prioritize embedded or appliance fleets using Renesas R-Car PCI endpoint hardware.
If patching is delayed, check vendor guidance for supported risk-reduction options.
Validation and detection
Inventory systems for Renesas R-Car PCI endpoint driver usage.
Compare kernel versions and packages against vendor advisories and stable commits.
Review /proc/iomem for missing or malformed outbound memory resource names.
Confirm patched builds include the referenced upstream stable commits.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Potential ATT&CK relevance
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These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
0CVSS vectors
3Timeline events
1ADP providers
10Source links
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
CVE publishedCVE Program
The CVE record was published.
Feb 27, 2025, 20:00 UTC (UTC+00:00)
CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.