CVE-2022-49894

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

cxl/region: Fix region HPA ordering validation

Some regions may not have any address space allocated. Skip them when validating HPA order otherwise a crash like the following may result:

devm_cxl_add_region: cxl_acpi cxl_acpi.0: decoder3.4: created region9 BUG: kernel NULL pointer dereference, address: 0000000000000000 [..] RIP: 0010:store_targetN+0x655/0x1740 [cxl_core] [..] Call Trace: <TASK> kernfs_fop_write_iter+0x144/0x200 vfs_write+0x24a/0x4d0 ksys_write+0x69/0xf0 do_syscall_64+0x3a/0x90

store_targetN+0x655/0x1740: alloc_region_ref at drivers/cxl/core/region.c:676 (inlined by) cxl_port_attach_region at drivers/cxl/core/region.c:850 (inlined by) cxl_region_attach at drivers/cxl/core/region.c:1290 (inlined by) attach_target at drivers/cxl/core/region.c:1410 (inlined by) store_targetN at drivers/cxl/core/region.c:1453

A NULL pointer dereference was fixed in alloc_region_ref() in the cxl_region driver, which could occur when validating Host Physical Address (HPA) ordering for regions without address space allocated. The issue was triggered by attempting to access a NULL res field. Triggering this vulnerability requires privileged access to configure or modify CXL regions via sysfs interfaces, which is generally restricted to administrative users (root or equivalent).

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.