Entreprise française de cybersécurité depuis 2004
☎ 03 60 47 09 81 - info@securiteinfo.com
☎ 03 60 47 09 81 - info@securiteinfo.com
In the Linux kernel, the following vulnerability has been resolved:x86/microcode/AMD: Fix out-of-bounds on systems with CPU-less NUMA nodesCurrently, load_microcode_amd() iterates over all NUMA nodes, retrieves theirCPU masks and unconditionally accesses per-CPU data for the first CPU of eachmask.According to Documentation/admin-guide/mm/numaperf.rst: "Some memory may share the same node as a CPU, and others are provided as memory only nodes."Therefore, some node CPU masks may be empty and wouldn't have a "first CPU".On a machine with far memory (and therefore CPU-less NUMA nodes):- cpumask_of_node(nid) is 0- cpumask_first(0) is CONFIG_NR_CPUS- cpu_data(CONFIG_NR_CPUS) accesses the cpu_info per-CPU array at an index that is 1 out of boundsThis does not have any security implications since flashing microcode isa privileged operation but I believe this has reliability implications bypotentially corrupting memory while flashing a microcode update.When booting with CONFIG_UBSAN_BOUNDS=y on an AMD machine that flashesa microcode update. I get the following splat: UBSAN: array-index-out-of-bounds in arch/x86/kernel/cpu/microcode/amd.c:X:Y index 512 is out of range for type 'unsigned long[512]' [...] Call Trace: dump_stack __ubsan_handle_out_of_bounds load_microcode_amd request_microcode_amd reload_store kernfs_fop_write_iter vfs_write ksys_write do_syscall_64 entry_SYSCALL_64_after_hwframeChange the loop to go over only NUMA nodes which have CPUs before determiningwhether the first CPU on the respective node needs microcode update. [ bp: Massage commit message, fix typo. ]
No PoCs from references.
- https://github.com/fkie-cad/nvd-json-data-feeds
- https://github.com/runwhen-contrib/helm-charts
- https://github.com/w4zu/Debian_security