CVE-2026-80917

Summary

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]

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/5e52eb0290f66ba0732956dcb1e365b5ca3c5108
• https://git.kernel.org/stable/c/baf9b0383ff770fdff123d3a832f3a99641d96dd
• https://git.kernel.org/stable/c/8d08713ec83a18526d1ed1fd5f0d2b901d103a10
• https://git.kernel.org/stable/c/74456843f18ba7f3045974d7e8b88ab993152b8c
• https://git.kernel.org/stable/c/0c55707bd5d0d7670704cfd0dda933809b052f67
• https://git.kernel.org/stable/c/a199293f3038db8d31d47aa60f1e18272cd82354
• https://git.kernel.org/stable/c/0916948026f623844acd08888f7cbedbf1c48d6b
• https://git.kernel.org/stable/c/008cb88edb41f3c7c8e0ed763ff9f26719830984

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