In the Linux kernel, the following vulnerability has been resolved:
resource: fix region_intersects() vs add_memory_driver_managed()
On a system with CXL memory, the resource tree (/proc/iomem) related to CXL memory may look like something as follows.
490000000-50fffffff : CXL Window 0 490000000-50fffffff : region0 490000000-50fffffff : dax0.0 490000000-50fffffff : System RAM (kmem)
Because drivers/dax/kmem.c calls add_memory_driver_managed() during onlining CXL memory, which makes "System RAM (kmem)" a descendant of "CXL Window X". This confuses region_intersects(), which expects all "System RAM" resources to be at the top level of iomem_resource. This can lead to bugs.
For example, when the following command line is executed to write some memory in CXL memory range via /dev/mem,
$ dd if=data of=/dev/mem bs=$((1 << 10)) seek=$((0x490000000 >> 10)) count=1 dd: error writing '/dev/mem': Bad address 1+0 records in 0+0 records out 0 bytes copied, 0.0283507 s, 0.0 kB/s
the command fails as expected. However, the error code is wrong. It should be "Operation not permitted" instead of "Bad address". More seriously, the /dev/mem permission checking in devmem_is_allowed() passes incorrectly. Although the accessing is prevented later because ioremap() isn't allowed to map system RAM, it is a potential security issue. During command executing, the following warning is reported in the kernel log for calling ioremap() on system RAM.
ioremap on RAM at 0x0000000490000000 - 0x0000000490000fff WARNING: CPU: 2 PID: 416 at arch/x86/mm/ioremap.c:216 __ioremap_caller.constprop.0+0x131/0x35d Call Trace: memremap+0xcb/0x184 xlate_dev_mem_ptr+0x25/0x2f write_mem+0x94/0xfb vfs_write+0x128/0x26d ksys_write+0xac/0xfe do_syscall_64+0x9a/0xfd entry_SYSCALL_64_after_hwframe+0x4b/0x53
The details of command execution process are as follows. In the above resource tree, "System RAM" is a descendant of "CXL Window 0" instead of a top level resource. So, region_intersects() will report no System RAM resources in the CXL memory region incorrectly, because it only checks the top level resources. Consequently, devmem_is_allowed() will return 1 (allow access via /dev/mem) for CXL memory region incorrectly. Fortunately, ioremap() doesn't allow to map System RAM and reject the access.
So, region_intersects() needs to be fixed to work correctly with the resource tree with "System RAM" not at top level as above. To fix it, if we found a unmatched resource in the top level, we will continue to search matched resources in its descendant resources. So, we will not miss any matched resources in resource tree anymore.
In the new implementation, an example resource tree
|------------- "CXL Window 0" ------------| |-- "System RAM" --|
will behave similar as the following fake resource tree for region_intersects(, IORESOURCE_SYSTEM_RAM, ),
|-- "System RAM" --||-- "CXL Window 0a" --|
Where "CXL Window 0a" is part of the original "CXL Window 0" that isn't covered by "System RAM".
CVSS Details
- CVSS 3.1 Base Score: 5.5
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon Linux Ami 2 | — | Upgrade kernel-debuginfoUpgrade kernel-livepatch-5.10.227-219.884Upgrade kernel-tools-debuginfoUpgrade python-perf-debuginfoUpgrade kernel-livepatch-5.15.168-114.166Upgrade kernel-headersUpgrade perf-debuginfoUpgrade kernelUpgrade kernel-debuginfo-common-x86_64Upgrade kernel-tools-develUpgrade python-perfUpgrade kernel-debuginfo-common-aarch64Upgrade bpftoolUpgrade kernel-toolsUpgrade kernel-develUpgrade bpftool-debuginfoUpgrade perf | Mar 14, 2025 | Oct 21, 2024 |
| Amazon_linux_2023 | — | Upgrade kernel-tools-develUpgrade bpftoolUpgrade kernelUpgrade kernel-toolsUpgrade kernel-libbpf-develUpgrade kernel-debuginfo-common-aarch64Upgrade python3-perf-debuginfoUpgrade kernel-livepatch-6.1.115-126.197Upgrade kernel-debuginfo-common-x86_64Upgrade kernel-develUpgrade python3-perfUpgrade kernel-libbpf-staticUpgrade kernel-modules-extra-commonUpgrade perf-debuginfoUpgrade perfUpgrade kernel-tools-debuginfoUpgrade kernel-libbpfUpgrade kernel-modules-extraUpgrade kernel-headersUpgrade bpftool-debuginfoUpgrade kernel-debuginfo | Mar 27, 2025 | Oct 21, 2024 |
| Debian | — | Upgrade linuxUpgrade linux-6.1 | Nov 11, 2024 | Oct 21, 2024 |
| Huawei Euleros 2_0_sp11 | — | Upgrade kernel-toolsUpgrade kernelUpgrade bpftoolUpgrade kernel-tools-libsUpgrade kernel-abi-stablelistsUpgrade python3-perf | Feb 11, 2025 | Oct 21, 2024 |
| Huawei Euleros 2_0_sp12 | — | Upgrade kernel-tools-libsUpgrade python3-perfUpgrade bpftoolUpgrade kernel-toolsUpgrade kernel-abi-stablelistsUpgrade kernel | Feb 11, 2025 | Oct 21, 2024 |
| Oracle_linux | — | Upgrade kernel-uek | Dec 17, 2024 | Oct 21, 2024 |
| Redhat_linux | — | Upgrade kernel-rtNo solution existsUpgrade kernel | May 15, 2025 | Oct 21, 2024 |
| Ubuntu | — | Upgrade linux-image-oem-22.04aUpgrade linux-image-oracle-64k-lts-24.04Upgrade linux-image-azure-lts-20.04Upgrade linux-image-raspi-nolpaeUpgrade linux-image-6.11.0-18-generic-64kUpgrade linux-image-5.4.0-208-generic-lpaeUpgrade linux-image-5.15.0-1072-gcpUpgrade linux-image-5.4.0-1058-xilinx-zynqmpUpgrade linux-image-5.15.0-1070-gkeUpgrade linux-image-lowlatencyUpgrade linux-image-oracle-lts-20.04Upgrade linux-image-6.8.0-1022-nvidia-lowlatencyUpgrade linux-image-generic-64k-hwe-24.04Upgrade linux-image-5.15.0-1068-nvidiaUpgrade linux-image-5.4.0-208-lowlatencyUpgrade linux-image-nvidia-64k-hwe-22.04Upgrade linux-image-6.8.0-54-genericUpgrade linux-image-bluefieldUpgrade linux-image-5.4.0-1129-raspiUpgrade linux-image-lowlatency-64k-hwe-20.04Upgrade linux-image-oemUpgrade linux-image-oem-24.04bUpgrade linux-image-6.11.0-1011-oracle-64kUpgrade linux-image-nvidiaUpgrade linux-image-6.8.0-57-generic-64kUpgrade linux-image-azure-nvidiaUpgrade linux-image-gcp-64k-lts-24.04Upgrade linux-image-lowlatency-hwe-22.04Upgrade linux-image-lowlatency-hwe-18.04Upgrade linux-image-generic-64kUpgrade linux-image-5.4.0-1145-azureUpgrade linux-image-5.15.0-1071-oracleUpgrade linux-image-xilinx-zynqmpUpgrade linux-image-5.4.0-1099-bluefieldUpgrade linux-image-oem-20.04bUpgrade linux-image-snapdragon-hwe-18.04Upgrade linux-image-nvidia-64k-6.8Upgrade linux-image-6.11.0-1008-raspiUpgrade linux-image-nvidia-hwe-22.04Upgrade linux-image-6.8.0-1020-oracle-64kUpgrade linux-image-6.8.0-1025-azureUpgrade linux-image-generic-lpaeUpgrade linux-image-gkeUpgrade linux-image-azure-lts-22.04Upgrade linux-image-oracle-lts-24.04Upgrade linux-image-6.8.0-1014-azure-nvidiaUpgrade linux-image-6.11.0-1005-realtimeUpgrade linux-image-6.8.0-1023-awsUpgrade linux-image-oem-20.04Upgrade linux-image-intelUpgrade linux-image-gke-5.15Upgrade linux-image-5.15.0-1071-intel-iotgUpgrade linux-image-lowlatency-hwe-20.04Upgrade linux-image-fipsUpgrade linux-image-virtualUpgrade linux-image-gkeop-6.8Upgrade linux-image-genericUpgrade linux-image-ibmUpgrade linux-image-6.8.0-54-generic-64kUpgrade linux-image-oracleUpgrade linux-image-gcp-lts-22.04Upgrade linux-image-6.11.0-1009-gcpUpgrade linux-image-5.15.0-1073-awsUpgrade linux-image-gkeopUpgrade linux-image-6.11.0-1009-awsUpgrade linux-image-nvidia-lowlatencyUpgrade linux-image-nvidia-lowlatency-64kUpgrade linux-image-6.8.0-57-genericUpgrade linux-image-ibm-lts-20.04Upgrade linux-image-5.15.0-1066-ibmUpgrade linux-image-6.8.0-1022-nvidiaUpgrade linux-image-nvidia-6.8Upgrade linux-image-oem-22.04Upgrade linux-image-5.4.0-1127-kvmUpgrade linux-image-generic-64k-hwe-20.04Upgrade linux-image-5.15.0-1039-xilinx-zynqmpUpgrade linux-image-generic-64k-hwe-22.04Upgrade linux-image-5.15.0-1078-azureUpgrade linux-image-5.15.0-127-generic-lpaeUpgrade linux-image-6.11.0-1009-azureUpgrade linux-image-lowlatency-64kUpgrade linux-image-gcp-lts-20.04Upgrade linux-image-6.11.0-1009-azure-fdeUpgrade linux-image-6.8.0-54-lowlatency-64kUpgrade linux-image-5.15.0-1056-gkeopUpgrade linux-image-6.8.0-54-lowlatencyUpgrade linux-image-lowlatency-64k-hwe-22.04Upgrade linux-image-raspi2Upgrade linux-image-5.15.0-127-genericUpgrade linux-image-virtual-hwe-18.04Upgrade linux-image-realtime-hwe-24.04Upgrade linux-image-6.8.0-1022-ibmUpgrade linux-image-5.4.0-1048-iotUpgrade linux-image-azure-cvmUpgrade linux-image-6.8.0-1024-oemUpgrade linux-image-6.8.0-1019-gkeUpgrade linux-image-oem-24.04aUpgrade linux-image-raspi-hwe-18.04Upgrade linux-image-nvidia-64kUpgrade linux-image-6.11.0-1010-lowlatency-64kUpgrade linux-image-5.15.0-1066-raspiUpgrade linux-image-generic-hwe-20.04Upgrade linux-image-oem-22.04bUpgrade linux-image-gcpUpgrade linux-image-azure-fde-lts-24.04Upgrade linux-image-6.11.0-18-genericUpgrade linux-image-5.4.0-1140-awsUpgrade linux-image-5.4.0-1142-awsUpgrade linux-image-5.4.0-1116-fipsUpgrade linux-image-oem-20.04cUpgrade linux-image-6.8.0-1024-gcp-64kUpgrade linux-image-realtimeUpgrade linux-image-aws-lts-20.04Upgrade linux-image-raspiUpgrade linux-image-5.4.0-1086-ibmUpgrade linux-image-5.15.0-127-lowlatencyUpgrade linux-image-5.4.0-1138-oracleUpgrade linux-image-aws-lts-22.04Upgrade linux-image-5.15.0-1070-kvmUpgrade linux-image-virtual-hwe-22.04Upgrade linux-image-awsUpgrade linux-image-gcp-64kUpgrade linux-image-aws-lts-24.04Upgrade linux-image-6.8.0-1025-azure-fdeUpgrade linux-image-oracle-64kUpgrade linux-image-virtual-hwe-24.04Upgrade linux-image-oem-24.04Upgrade linux-image-generic-lpae-hwe-20.04Upgrade linux-image-generic-hwe-24.04Upgrade linux-image-6.11.0-1011-oracleUpgrade linux-image-azure-lts-24.04Upgrade linux-image-6.11.0-1010-lowlatencyUpgrade linux-image-6.8.0-1024-gcpUpgrade linux-image-oem-osp1Upgrade linux-image-5.15.0-127-generic-64kUpgrade linux-image-5.15.0-1068-nvidia-lowlatencyUpgrade linux-image-6.11.0-1015-oemUpgrade linux-image-oem-22.04cUpgrade linux-image-generic-hwe-22.04Upgrade linux-image-generic-hwe-18.04Upgrade linux-image-6.8.0-1022-nvidia-64kUpgrade linux-image-5.15.0-127-lowlatency-64kUpgrade linux-image-oracle-lts-22.04Upgrade linux-image-oem-22.04dUpgrade linux-image-gkeop-5.15Upgrade linux-image-6.8.0-1020-oracleUpgrade linux-image-6.8.0-1006-gkeopUpgrade linux-image-virtual-hwe-20.04Upgrade linux-image-ibm-lts-24.04Upgrade linux-image-ibm-classicUpgrade linux-image-azureUpgrade linux-image-5.4.0-1143-gcpUpgrade linux-image-6.8.0-1022-nvidia-lowlatency-64kUpgrade linux-image-6.8.0-1019-raspiUpgrade linux-image-5.4.0-208-genericUpgrade linux-image-oem-20.04dUpgrade linux-image-intel-iotgUpgrade linux-image-azure-fdeUpgrade linux-image-kvmUpgrade linux-image-gcp-lts-24.04 | Dec 18, 2024 | Oct 21, 2024 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Oct 14, 2025 | Oct 21, 2024 |
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