CVE-2024-41085

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> cxl/mem: Fix no cxl_nvd during pmem region auto-assembling<br /> <br /> When CXL subsystem is auto-assembling a pmem region during cxl<br /> endpoint port probing, always hit below calltrace.<br /> <br /> BUG: kernel NULL pointer dereference, address: 0000000000000078<br /> #PF: supervisor read access in kernel mode<br /> #PF: error_code(0x0000) - not-present page<br /> RIP: 0010:cxl_pmem_region_probe+0x22e/0x360 [cxl_pmem]<br /> Call Trace:<br /> <br /> ? __die+0x24/0x70<br /> ? page_fault_oops+0x82/0x160<br /> ? do_user_addr_fault+0x65/0x6b0<br /> ? exc_page_fault+0x7d/0x170<br /> ? asm_exc_page_fault+0x26/0x30<br /> ? cxl_pmem_region_probe+0x22e/0x360 [cxl_pmem]<br /> ? cxl_pmem_region_probe+0x1ac/0x360 [cxl_pmem]<br /> cxl_bus_probe+0x1b/0x60 [cxl_core]<br /> really_probe+0x173/0x410<br /> ? __pfx___device_attach_driver+0x10/0x10<br /> __driver_probe_device+0x80/0x170<br /> driver_probe_device+0x1e/0x90<br /> __device_attach_driver+0x90/0x120<br /> bus_for_each_drv+0x84/0xe0<br /> __device_attach+0xbc/0x1f0<br /> bus_probe_device+0x90/0xa0<br /> device_add+0x51c/0x710<br /> devm_cxl_add_pmem_region+0x1b5/0x380 [cxl_core]<br /> cxl_bus_probe+0x1b/0x60 [cxl_core]<br /> <br /> The cxl_nvd of the memdev needs to be available during the pmem region<br /> probe. Currently the cxl_nvd is registered after the endpoint port probe.<br /> The endpoint probe, in the case of autoassembly of regions, can cause a<br /> pmem region probe requiring the not yet available cxl_nvd. Adjust the<br /> sequence so this dependency is met.<br /> <br /> This requires adding a port parameter to cxl_find_nvdimm_bridge() that<br /> can be used to query the ancestor root port. The endpoint port is not<br /> yet available, but will share a common ancestor with its parent, so<br /> start the query from there instead.