In the Linux kernel, the following vulnerability has been resolved:
PCI: host-generic: Fix NULL pointer dereference on 32-bit CAM systems
On 32-bit systems the config space is too large to ioremap in one go, so
pci_ecam_create() maps each bus segment separately and relies on the
->add_bus callback (pci_ecam_add_bus) to populate the per-bus mapping in
cfg->winp[]. pci_ecam_map_bus() then uses that mapping as the base for
every config access.
The generic ECAM ops (pci_generic_ecam_ops) already provide the ->add_bus
and ->remove_bus callbacks, but the CAM (legacy) ops in pci-host-generic.c
do not. As a result, on a 32-bit host using "pci-host-cam-generic" the
per-bus mapping is never set up and the first config read dereferences a
NULL base, crashing during bus enumeration:
Unable to handle kernel NULL pointer dereference at virtual address 00000800
Oops [#1]
CPU: 0 PID: 1 Comm: swapper Not tainted 6.9.7+ #43
Hardware name: Digilent Nexys-Video-A7 RV32 (DT)
epc : pci_generic_config_read+0x40/0xb0
ra : pci_generic_config_read+0x2c/0xb0
[<c038db9c>] pci_generic_config_read+0x40/0xb0
[<c038da04>] pci_bus_read_config_dword+0x50/0xb0
[<c0391e94>] pci_bus_generic_read_dev_vendor_id+0x3c/0x1ec
[<c039245c>] pci_scan_single_device+0xa4/0x11c
[<c0392570>] pci_scan_slot+0x9c/0x23c
[<c039388c>] pci_scan_child_bus_extend+0x58/0x2f4
[<c0393db0>] pci_scan_root_bus_bridge+0x64/0xe8
[<c0393e54>] pci_host_probe+0x20/0xc8
[<c03bc6f4>] pci_host_common_probe+0x144/0x1e4
Fix this by giving the CAM ops the same ->add_bus/->remove_bus callbacks.
Since pci_ecam_add_bus() and pci_ecam_remove_bus() are static to ecam.c,
move the CAM ops definition there as pci_generic_cam_ops (mirroring
pci_generic_ecam_ops) and export it for pci-host-generic.c to reference.
[mani: removed timestamp from log]
PCI: host-generic: Fix NULL pointer dereference on 32-bit CAM systems
On 32-bit systems the config space is too large to ioremap in one go, so
pci_ecam_create() maps each bus segment separately and relies on the
->add_bus callback (pci_ecam_add_bus) to populate the per-bus mapping in
cfg->winp[]. pci_ecam_map_bus() then uses that mapping as the base for
every config access.
The generic ECAM ops (pci_generic_ecam_ops) already provide the ->add_bus
and ->remove_bus callbacks, but the CAM (legacy) ops in pci-host-generic.c
do not. As a result, on a 32-bit host using "pci-host-cam-generic" the
per-bus mapping is never set up and the first config read dereferences a
NULL base, crashing during bus enumeration:
Unable to handle kernel NULL pointer dereference at virtual address 00000800
Oops [#1]
CPU: 0 PID: 1 Comm: swapper Not tainted 6.9.7+ #43
Hardware name: Digilent Nexys-Video-A7 RV32 (DT)
epc : pci_generic_config_read+0x40/0xb0
ra : pci_generic_config_read+0x2c/0xb0
[<c038db9c>] pci_generic_config_read+0x40/0xb0
[<c038da04>] pci_bus_read_config_dword+0x50/0xb0
[<c0391e94>] pci_bus_generic_read_dev_vendor_id+0x3c/0x1ec
[<c039245c>] pci_scan_single_device+0xa4/0x11c
[<c0392570>] pci_scan_slot+0x9c/0x23c
[<c039388c>] pci_scan_child_bus_extend+0x58/0x2f4
[<c0393db0>] pci_scan_root_bus_bridge+0x64/0xe8
[<c0393e54>] pci_host_probe+0x20/0xc8
[<c03bc6f4>] pci_host_common_probe+0x144/0x1e4
Fix this by giving the CAM ops the same ->add_bus/->remove_bus callbacks.
Since pci_ecam_add_bus() and pci_ecam_remove_bus() are static to ecam.c,
move the CAM ops definition there as pci_generic_cam_ops (mirroring
pci_generic_ecam_ops) and export it for pci-host-generic.c to reference.
[mani: removed timestamp from log]
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Fixes
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References
History
Wed, 09 Sep 2026 16:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: PCI: host-generic: Fix NULL pointer dereference on 32-bit CAM systems On 32-bit systems the config space is too large to ioremap in one go, so pci_ecam_create() maps each bus segment separately and relies on the ->add_bus callback (pci_ecam_add_bus) to populate the per-bus mapping in cfg->winp[]. pci_ecam_map_bus() then uses that mapping as the base for every config access. The generic ECAM ops (pci_generic_ecam_ops) already provide the ->add_bus and ->remove_bus callbacks, but the CAM (legacy) ops in pci-host-generic.c do not. As a result, on a 32-bit host using "pci-host-cam-generic" the per-bus mapping is never set up and the first config read dereferences a NULL base, crashing during bus enumeration: Unable to handle kernel NULL pointer dereference at virtual address 00000800 Oops [#1] CPU: 0 PID: 1 Comm: swapper Not tainted 6.9.7+ #43 Hardware name: Digilent Nexys-Video-A7 RV32 (DT) epc : pci_generic_config_read+0x40/0xb0 ra : pci_generic_config_read+0x2c/0xb0 [<c038db9c>] pci_generic_config_read+0x40/0xb0 [<c038da04>] pci_bus_read_config_dword+0x50/0xb0 [<c0391e94>] pci_bus_generic_read_dev_vendor_id+0x3c/0x1ec [<c039245c>] pci_scan_single_device+0xa4/0x11c [<c0392570>] pci_scan_slot+0x9c/0x23c [<c039388c>] pci_scan_child_bus_extend+0x58/0x2f4 [<c0393db0>] pci_scan_root_bus_bridge+0x64/0xe8 [<c0393e54>] pci_host_probe+0x20/0xc8 [<c03bc6f4>] pci_host_common_probe+0x144/0x1e4 Fix this by giving the CAM ops the same ->add_bus/->remove_bus callbacks. Since pci_ecam_add_bus() and pci_ecam_remove_bus() are static to ecam.c, move the CAM ops definition there as pci_generic_cam_ops (mirroring pci_generic_ecam_ops) and export it for pci-host-generic.c to reference. [mani: removed timestamp from log] | |
| Title | PCI: host-generic: Fix NULL pointer dereference on 32-bit CAM systems | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
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Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-09T16:13:15.202Z
Reserved: 2026-08-26T14:34:25.801Z
Link: CVE-2026-80917
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-09T17:17:46.680
Modified: 2026-09-09T17:17:46.680
Link: CVE-2026-80917
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.