{"cve":"CVE-2022-50635","nvd":{"published":"2025-12-09T01:16:45.717","modified":"2026-06-17T05:23:54.430","status":"Deferred","description":"In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/kprobes: Fix null pointer reference in arch_prepare_kprobe()\n\nI found a null pointer reference in arch_prepare_kprobe():\n\n  # echo 'p cmdline_proc_show' > kprobe_events\n  # echo 'p cmdline_proc_show+16' >> kprobe_events\n  Kernel attempted to read user page (0) - exploit attempt? (uid: 0)\n  BUG: Kernel NULL pointer dereference on read at 0x00000000\n  Faulting instruction address: 0xc000000000050bfc\n  Oops: Kernel access of bad area, sig: 11 [#1]\n  LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV\n  Modules linked in:\n  CPU: 0 PID: 122 Comm: sh Not tainted 6.0.0-rc3-00007-gdcf8e5633e2e #10\n  NIP:  c000000000050bfc LR: c000000000050bec CTR: 0000000000005bdc\n  REGS: c0000000348475b0 TRAP: 0300   Not tainted  (6.0.0-rc3-00007-gdcf8e5633e2e)\n  MSR:  9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE>  CR: 88002444  XER: 20040006\n  CFAR: c00000000022d100 DAR: 0000000000000000 DSISR: 40000000 IRQMASK: 0\n  ...\n  NIP arch_prepare_kprobe+0x10c/0x2d0\n  LR  arch_prepare_kprobe+0xfc/0x2d0\n  Call Trace:\n    0xc0000000012f77a0 (unreliable)\n    register_kprobe+0x3c0/0x7a0\n    __register_trace_kprobe+0x140/0x1a0\n    __trace_kprobe_create+0x794/0x1040\n    trace_probe_create+0xc4/0xe0\n    create_or_delete_trace_kprobe+0x2c/0x80\n    trace_parse_run_command+0xf0/0x210\n    probes_write+0x20/0x40\n    vfs_write+0xfc/0x450\n    ksys_write+0x84/0x140\n    system_call_exception+0x17c/0x3a0\n    system_call_vectored_common+0xe8/0x278\n  --- interrupt: 3000 at 0x7fffa5682de0\n  NIP:  00007fffa5682de0 LR: 0000000000000000 CTR: 0000000000000000\n  REGS: c000000034847e80 TRAP: 3000   Not tainted  (6.0.0-rc3-00007-gdcf8e5633e2e)\n  MSR:  900000000280f033 <SF,HV,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE>  CR: 44002408  XER: 00000000\n\nThe address being probed has some special:\n\n  cmdline_proc_show: Probe based on ftrace\n  cmdline_proc_show+16: Probe for the next instruction at the ftrace location\n\nThe ftrace-based kprobe does not generate kprobe::ainsn::insn, it gets\nset to NULL. In arch_prepare_kprobe() it will check for:\n\n  ...\n  prev = get_kprobe(p->addr - 1);\n  preempt_enable_no_resched();\n  if (prev && ppc_inst_prefixed(ppc_inst_read(prev->ainsn.insn))) {\n  ...\n\nIf prev is based on ftrace, 'ppc_inst_read(prev->ainsn.insn)' will occur\nwith a null pointer reference. At this point prev->addr will not be a\nprefixed instruction, so the check can be skipped.\n\nCheck if prev is ftrace-based kprobe before reading 'prev->ainsn.insn'\nto fix this problem.\n\n[mpe: Trim oops]","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/4eac4f6a86ae73ef4b772d37398beeba2fbfde4e","https://git.kernel.org/stable/c/5fd1b369387c53ee6c774ab86e32e362a1e537ac","https://git.kernel.org/stable/c/7f536a8cb62dd5c084f112373fc34cdb5168a813","https://git.kernel.org/stable/c/97f88a3d723162781d6cbfdc7b9617eefab55b19"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:16:40.427100871+00:00"},"epss":{"cve":"CVE-2022-50635","score":0.00204,"percentile":0.10354,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}