CVE-2025-39903

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

of_numa: fix uninitialized memory nodes causing kernel panic

When there are memory-only nodes (nodes without CPUs), these nodes are not properly initialized, causing kernel panic during boot.

of_numa_init of_numa_parse_cpu_nodes node_set(nid, numa_nodes_parsed); of_numa_parse_memory_nodes

In of_numa_parse_cpu_nodes, numa_nodes_parsed gets updated only for nodes containing CPUs. Memory-only nodes should have been updated in of_numa_parse_memory_nodes, but they weren't.

Subsequently, when free_area_init() attempts to access NODE_DATA() for these uninitialized memory nodes, the kernel panics due to NULL pointer dereference.

This can be reproduced on ARM64 QEMU with 1 CPU and 2 memory nodes:

qemu-system-aarch64
-cpu host -nographic
-m 4G -smp 1
-machine virt,accel=kvm,gic-version=3,iommu=smmuv3
-object memory-backend-ram,size=2G,id=mem0
-object memory-backend-ram,size=2G,id=mem1
-numa node,nodeid=0,memdev=mem0
-numa node,nodeid=1,memdev=mem1
-kernel $IMAGE
-hda $DISK
-append "console=ttyAMA0 root=/dev/vda rw earlycon"

[ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x481fd010] [ 0.000000] Linux version 6.17.0-rc1-00001-gabb4b3daf18c-dirty (yintirui@local) (gcc (GCC) 12.3.1, GNU ld (GNU Binutils) 2.41) #52 SMP PREEMPT Mon Aug 18 09:49:40 CST 2025 [ 0.000000] KASLR enabled [ 0.000000] random: crng init done [ 0.000000] Machine model: linux,dummy-virt [ 0.000000] efi: UEFI not found. [ 0.000000] earlycon: pl11 at MMIO 0x0000000009000000 (options '') [ 0.000000] printk: legacy bootconsole [pl11] enabled [ 0.000000] OF: reserved mem: Reserved memory: No reserved-memory node in the DT [ 0.000000] NODE_DATA(0) allocated [mem 0xbfffd9c0-0xbfffffff] [ 0.000000] node 1 must be removed before remove section 23 [ 0.000000] Zone ranges: [ 0.000000] DMA [mem 0x0000000040000000-0x00000000ffffffff] [ 0.000000] DMA32 empty [...