CVE-2024-49878 — resource: fix region_intersects() vs add_memory_driver_managed()

Affected: Linux

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 0x00…

USN-7166-1 — linux, linux-gcp, linux-gcp-5.15, linux-gke, linux-gkeop, linux-ibm, linux-ibm-5.15, linux-kvm, linux-lowlatency, linux…

Affected: Ubuntu:20.04:LTS: linux-gcp-5.15, Ubuntu:20.04:LTS: linux-ibm-5.15, Ubuntu:20.04:LTS: linux-lowlatency-hwe-5.15, Ubuntu:20.04:LTS: linux-oracle-5.15, Ubuntu:22.04:LTS: linux, Ubuntu:22.04:LTS: linux-gcp, Ubuntu:22.04:LTS: linux-gke, Ubuntu:22.04:LTS: linux-gkeop, Ubuntu:22.04:LTS: linux-ibm, Ubuntu:22.04:LTS: linux-kvm and 4 more

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM32 architecture; - RISC-V architecture; - S390 architecture; - x86 architecture; - Block layer subsystem; - ACPI drivers; - Drivers core; - ATA over ethernet (AOE) driver; - TPM device driver; - Clock framework and drivers; - Buffer Sharing and Synchronization framework; - EFI core; - GPIO subsystem; - GPU drivers; - HID subsystem; - I2C subsystem; - InfiniBand drivers; - Input Device core drivers; - Mailbox framework; - Media drivers; - Ethernet bonding driver; - Network drivers; - Mellanox network drivers; - Microsoft Azure Network Adapter (MANA) driver; - STMicroelectronics network drivers; - NTB driver; - Virtio pmem driver; - PCI subsystem; - x86 platform drivers; - S/390 drivers; - SCSI subsystem; - SPI subsystem; - Thermal drivers; - USB Device Class drivers; - USB Type-C Port Controller Manager driver; - VFIO drivers; - Virtio Host (VHOST) subsystem; - Framebuffer layer; - 9P distributed file system; - BTRFS file system; - Ceph distributed file system; - File systems infrastructure; - Ext4 file system; - F2FS file system; - GFS2 file system; - JFS file system; - Network file system (NFS) client; - Network file system (NFS) server daemon; - NILFS2 file system; - Network file system (NFS)…

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CVE-2024-49878 — resource: fix region_intersects() vs add_memory_driver_managed()

USN-7166-1 — linux, linux-gcp, linux-gcp-5.15, linux-gke, linux-gkeop, linux-ibm, linux-ibm-5.15, linux-kvm, linux-lowlatency, linux…