CVE-2025-22031
PCI/bwctrl: Fix NULL pointer dereference on bus number exhaustion
Published Apr 16, 2025
CVSS 3.1 · 5.5 Medium
EPSS < 1%
KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:
PCI/bwctrl: Fix NULL pointer dereference on bus number exhaustion
When BIOS neglects to assign bus numbers to PCI bridges, the kernel
attempts to correct that during PCI device enumeration. If it runs out
of bus numbers, no pci_bus is allocated and the "subordinate" pointer in
the bridge's pci_dev remains NULL.
The PCIe bandwidth controller erroneously does not check for a NULL
subordinate pointer and dereferences it on probe.
Bandwidth control of unusable devices below the bridge is of questionable
utility, so simply error out instead. This mirrors what PCIe hotplug does
since commit 62e4492c3063 ("PCI: Prevent NULL dereference during pciehp
probe").
The PCI core emits a message with KERN_INFO severity if it has run out of
bus numbers. PCIe hotplug emits an additional message with KERN_ERR
severity to inform the user that hotplug functionality is disabled at the
bridge. A similar message for bandwidth control does not seem merited,
given that its only purpose so far is to expose an up-to-date link speed
in sysfs and throttle the link speed on certain laptops with limited
Thermal Design Power. So error out silently.
User-visible messages:
pci 0000:16:02.0: bridge configuration invalid ([bus 00-00]), reconfiguring
[...]
pci_bus 0000:45: busn_res: [bus 45-74] end is updated to 74
pci 0000:16:02.0: devices behind bridge are unusable because [bus 45-74] cannot be assigned for them
[...]
pcieport 0000:16:02.0: pciehp: Hotplug bridge without secondary bus, ignoring
[...]
BUG: kernel NULL pointer dereference
RIP: pcie_update_link_speed
pcie_bwnotif_enable
pcie_bwnotif_probe
pcie_port_probe_service
really_probe
PCI/bwctrl: Fix NULL pointer dereference on bus number exhaustion
When BIOS neglects to assign bus numbers to PCI bridges, the kernel
attempts to correct that during PCI device enumeration. If it runs out
of bus numbers, no pci_bus is allocated and the "subordinate" pointer in
the bridge's pci_dev remains NULL.
The PCIe bandwidth controller erroneously does not check for a NULL
subordinate pointer and dereferences it on probe.
Bandwidth control of unusable devices below the bridge is of questionable
utility, so simply error out instead. This mirrors what PCIe hotplug does
since commit 62e4492c3063 ("PCI: Prevent NULL dereference during pciehp
probe").
The PCI core emits a message with KERN_INFO severity if it has run out of
bus numbers. PCIe hotplug emits an additional message with KERN_ERR
severity to inform the user that hotplug functionality is disabled at the
bridge. A similar message for bandwidth control does not seem merited,
given that its only purpose so far is to expose an up-to-date link speed
in sysfs and throttle the link speed on certain laptops with limited
Thermal Design Power. So error out silently.
User-visible messages:
pci 0000:16:02.0: bridge configuration invalid ([bus 00-00]), reconfiguring
[...]
pci_bus 0000:45: busn_res: [bus 45-74] end is updated to 74
pci 0000:16:02.0: devices behind bridge are unusable because [bus 45-74] cannot be assigned for them
[...]
pcieport 0000:16:02.0: pciehp: Hotplug bridge without secondary bus, ignoring
[...]
BUG: kernel NULL pointer dereference
RIP: pcie_update_link_speed
pcie_bwnotif_enable
pcie_bwnotif_probe
pcie_port_probe_service
really_probe
Analysis
Affected Products
-
CVE record
-
NVD configurations
-
Red Hat packages
No data
-
OpenCVE enrichment
No data
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
||||||||||||||||||
| Linux | Linux | affected |
|
Configuration 1 [-]
|
No data.
No data available yet.
Remediation
Tracking
Advisories
| Source | ID | Title |
|---|---|---|
 EUVD |
EUVD-2025-11273 | In the Linux kernel, the following vulnerability has been resolved: PCI/bwctrl: Fix NULL pointer dereference on bus number exhaustion When BIOS neglects to assign bus numbers to PCI bridges, the kernel attempts to correct that during PCI device enumeration. If it runs out of bus numbers, no pci_bus is allocated and the "subordinate" pointer in the bridge's pci_dev remains NULL. The PCIe bandwidth controller erroneously does not check for a NULL subordinate pointer and dereferences it on probe. Bandwidth control of unusable devices below the bridge is of questionable utility, so simply error out instead. This mirrors what PCIe hotplug does since commit 62e4492c3063 ("PCI: Prevent NULL dereference during pciehp probe"). The PCI core emits a message with KERN_INFO severity if it has run out of bus numbers. PCIe hotplug emits an additional message with KERN_ERR severity to inform the user that hotplug functionality is disabled at the bridge. A similar message for bandwidth control does not seem merited, given that its only purpose so far is to expose an up-to-date link speed in sysfs and throttle the link speed on certain laptops with limited Thermal Design Power. So error out silently. User-visible messages: pci 0000:16:02.0: bridge configuration invalid ([bus 00-00]), reconfiguring [...] pci_bus 0000:45: busn_res: [bus 45-74] end is updated to 74 pci 0000:16:02.0: devices behind bridge are unusable because [bus 45-74] cannot be assigned for them [...] pcieport 0000:16:02.0: pciehp: Hotplug bridge without secondary bus, ignoring [...] BUG: kernel NULL pointer dereference RIP: pcie_update_link_speed pcie_bwnotif_enable pcie_bwnotif_probe pcie_port_probe_service really_probe |
 Ubuntu USN |
USN-7594-1 | Linux kernel vulnerabilities |
| Ubuntu USN |
USN-7594-2 | Linux kernel (Azure) vulnerabilities |
| Ubuntu USN |
USN-7594-3 | Linux kernel vulnerabilities |
Metrics
No CVSS v4.0
Attack Vector Local
Attack Complexity Low
Privileges Required Low
Scope Unchanged
Confidentiality Impact None
Integrity Impact None
Availability Impact High
User Interaction None
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.258% probability within 30 days)
Exploitation none
Automatable no
Technical Impact partial
References
History
Oct 1, 2025 6:15 PM
Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Apr 29, 2025 7:15 PM
First appearance in the feed. Weaknesses updated. Affected versions updated. Affected vendors updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux
Linux linux Kernel |
|
| Weaknesses | CWE-476 | |
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
Apr 17, 2025 2:15 PM
Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Apr 16, 2025 2:30 PM
Description updated. Title updated. Added references
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: PCI/bwctrl: Fix NULL pointer dereference on bus number exhaustion When BIOS neglects to assign bus numbers to PCI bridges, the kernel attempts to correct that during PCI device enumeration. If it runs out of bus numbers, no pci_bus is allocated and the "subordinate" pointer in the bridge's pci_dev remains NULL. The PCIe bandwidth controller erroneously does not check for a NULL subordinate pointer and dereferences it on probe. Bandwidth control of unusable devices below the bridge is of questionable utility, so simply error out instead. This mirrors what PCIe hotplug does since commit 62e4492c3063 ("PCI: Prevent NULL dereference during pciehp probe"). The PCI core emits a message with KERN_INFO severity if it has run out of bus numbers. PCIe hotplug emits an additional message with KERN_ERR severity to inform the user that hotplug functionality is disabled at the bridge. A similar message for bandwidth control does not seem merited, given that its only purpose so far is to expose an up-to-date link speed in sysfs and throttle the link speed on certain laptops with limited Thermal Design Power. So error out silently. User-visible messages: pci 0000:16:02.0: bridge configuration invalid ([bus 00-00]), reconfiguring [...] pci_bus 0000:45: busn_res: [bus 45-74] end is updated to 74 pci 0000:16:02.0: devices behind bridge are unusable because [bus 45-74] cannot be assigned for them [...] pcieport 0000:16:02.0: pciehp: Hotplug bridge without secondary bus, ignoring [...] BUG: kernel NULL pointer dereference RIP: pcie_update_link_speed pcie_bwnotif_enable pcie_bwnotif_probe pcie_port_probe_service really_probe | |
| Title | PCI/bwctrl: Fix NULL pointer dereference on bus number exhaustion | |
| References |
|
Subscriptions
Weaknesses
-
CWE-476
NULL Pointer Dereference
