diff options
| author | Steffen Persvold <spersvold@gmail.com> | 2026-07-09 14:24:46 +0200 |
|---|---|---|
| committer | Manivannan Sadhasivam <mani@kernel.org> | 2026-07-20 14:59:56 +0200 |
| commit | 008cb88edb41f3c7c8e0ed763ff9f26719830984 (patch) | |
| tree | a496ad4e2cd01b3fd6afb72e48a73d13ed09aa20 /include/linux | |
| parent | dc59e4fea9d83f03bad6bddf3fa2e52491777482 (diff) | |
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.
Fixes: 8fe55ef23387 ("PCI: Dynamically map ECAM regions")
Signed-off-by: Steffen Persvold <spersvold@gmail.com>
[mani: removed timestamp from log]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260709122446.3151899-1-spersvold@gmail.com
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/pci-ecam.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/pci-ecam.h b/include/linux/pci-ecam.h index d930651473b4..044f67ced6ff 100644 --- a/include/linux/pci-ecam.h +++ b/include/linux/pci-ecam.h @@ -81,6 +81,9 @@ void __iomem *pci_ecam_map_bus(struct pci_bus *bus, unsigned int devfn, /* default ECAM ops */ extern const struct pci_ecam_ops pci_generic_ecam_ops; +/* default CAM ops */ +extern const struct pci_ecam_ops pci_generic_cam_ops; + #if defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS) extern const struct pci_ecam_ops pci_32b_ops; /* 32-bit accesses only */ extern const struct pci_ecam_ops pci_32b_read_ops; /* 32-bit read only */ |