CVE-2024-41085 cxl/mem: Fix no cxl_nvd during pmem region auto-assembling
A null pointer dereference in the Linux kernel CXL memory driver causes a system crash during PMEM region auto-assembly.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-41085?
CVE-2024-41085 is a medium-severity vulnerability in Linux kernel, published on 29 Jul 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
cxl/mem: Fix no cxl_nvd during pmem region auto-assembling
When CXL subsystem is auto-assembling a pmem region during cxl endpoint port probing, always hit below calltrace.
BUG: kernel NULL pointer dereference, address: 0000000000000078 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page RIP: 0010:cxl_pmem_region_probe+0x22e/0x360 [cxl_pmem] Call Trace: <TASK> ? __die+0x24/0x70 ? page_fault_oops+0x82/0x160 ? do_user_addr_fault+0x65/0x6b0 ? exc_page_fault+0x7d/0x170 ? asm_exc_page_fault+0x26/0x30 ? cxl_pmem_region_probe+0x22e/0x360 [cxl_pmem] ? cxl_pmem_region_probe+0x1ac/0x360 [cxl_pmem] cxl_bus_probe+0x1b/0x60 [cxl_core] really_probe+0x173/0x410 ? __pfx___device_attach_driver+0x10/0x10 __driver_probe_device+0x80/0x170 driver_probe_device+0x1e/0x90 __device_attach_driver+0x90/0x120 bus_for_each_drv+0x84/0xe0 __device_attach+0xbc/0x1f0 bus_probe_device+0x90/0xa0 device_add+0x51c/0x710 devm_cxl_add_pmem_region+0x1b5/0x380 [cxl_core] cxl_bus_probe+0x1b/0x60 [cxl_core]
The cxl_nvd of the memdev needs to be available during the pmem region probe. Currently the cxl_nvd is registered after the endpoint port probe. The endpoint probe, in the case of autoassembly of regions, can cause a pmem region probe requiring the not yet available cxl_nvd. Adjust the sequence so this dependency is met.
This requires adding a port parameter to cxl_find_nvdimm_bridge() that can be used to query the ancestor root port. The endpoint port is not yet available, but will share a common ancestor with its parent, so start the query from there instead.
Weakness: CWE-476
Which versions are affected by CVE-2024-41085?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-41085?
Apply the vendor's patch.
Is CVE-2024-41085 being exploited?
There is no known exploitation of CVE-2024-41085 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-48057, BELL-CVE-2024-41085, DEBIAN-CVE-2024-41085, GHSA-2qvq-p8h3-vf5j, UBUNTU-CVE-2024-41085.