CVE-2024-26738

In the Linux kernel, the following vulnerability has been resolved:

powerpc/pseries/iommu: DLPAR add doesnt completely initialize pci_controller

When a PCI device is dynamically added, the kernel oopses with a NULL pointer dereference:

BUG: Kernel NULL pointer dereference on read at 0x00000030 Faulting instruction address: 0xc0000000006bbe5c Oops: Kernel access of bad area, sig: 11 [#1] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries Modules linked in: rpadlpar_io rpaphp rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace fscache netfs xsk_diag bonding nft_compat nf_tables nfnetlink rfkill binfmt_misc dm_multipath rpcrdma sunrpc rdma_ucm ib_srpt ib_isert iscsi_target_mod target_core_mod ib_umad ib_iser libiscsi scsi_transport_iscsi ib_ipoib rdma_cm iw_cm ib_cm mlx5_ib ib_uverbs ib_core pseries_rng drm drm_panel_orientation_quirks xfs libcrc32c mlx5_core mlxfw sd_mod t10_pi sg tls ibmvscsi ibmveth scsi_transport_srp vmx_crypto pseries_wdt psample dm_mirror dm_region_hash dm_log dm_mod fuse CPU: 17 PID: 2685 Comm: drmgr Not tainted 6.7.0-203405+ #66 Hardware name: IBM,9080-HEX POWER10 (raw) 0x800200 0xf000006 of:IBM,FW1060.00 (NH1060_008) hv:phyp pSeries NIP: c0000000006bbe5c LR: c000000000a13e68 CTR: c0000000000579f8 REGS: c00000009924f240 TRAP: 0300 Not tainted (6.7.0-203405+) MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 24002220 XER: 20040006 CFAR: c000000000a13e64 DAR: 0000000000000030 DSISR: 40000000 IRQMASK: 0 … NIP sysfs_add_link_to_group+0x34/0x94 LR iommu_device_link+0x5c/0x118 Call Trace: iommu_init_device+0x26c/0x318 (unreliable) iommu_device_link+0x5c/0x118 iommu_init_device+0xa8/0x318 iommu_probe_device+0xc0/0x134 iommu_bus_notifier+0x44/0x104 notifier_call_chain+0xb8/0x19c blocking_notifier_call_chain+0x64/0x98 bus_notify+0x50/0x7c device_add+0x640/0x918 pci_device_add+0x23c/0x298 of_create_pci_dev+0x400/0x884 of_scan_pci_dev+0x124/0x1b0 __of_scan_bus+0x78/0x18c pcibios_scan_phb+0x2a4/0x3b0 init_phb_dynamic+0xb8/0x110 dlpar_add_slot+0x170/0x3b8 [rpadlpar_io] add_slot_store.part.0+0xb4/0x130 [rpadlpar_io] kobj_attr_store+0x2c/0x48 sysfs_kf_write+0x64/0x78 kernfs_fop_write_iter+0x1b0/0x290 vfs_write+0x350/0x4a0 ksys_write+0x84/0x140 system_call_exception+0x124/0x330 system_call_vectored_common+0x15c/0x2ec

Commit a940904443e4 (powerpc/iommu: Add iommu_ops to report capabilities and allow blocking domains) broke DLPAR add of PCI devices.

The above added iommu_device structure to pci_controller. During system boot, PCI devices are discovered and this newly added iommu_device structure is initialized by a call to iommu_device_register().

During DLPAR add of a PCI device, a new pci_controller structure is allocated but there are no calls made to iommu_device_register() interface.

Fix is to register the iommu device during DLPAR add as well.

Weakness

The product dereferences a pointer that it expects to be valid but is NULL.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/46e36ebd5e00a148b67ed77c1d31675996f77c25
• https://git.kernel.org/stable/c/a5c57fd2e9bd1c8ea8613a8f94fd0be5eccbf321
• https://git.kernel.org/stable/c/b8315b2e25b4e68e42fcb74630f824b9a5067765
• https://git.kernel.org/stable/c/46e36ebd5e00a148b67ed77c1d31675996f77c25
• https://git.kernel.org/stable/c/a5c57fd2e9bd1c8ea8613a8f94fd0be5eccbf321
• https://git.kernel.org/stable/c/b8315b2e25b4e68e42fcb74630f824b9a5067765