In the Linux kernel, the following vulnerability has been resolved:
powerpc/kprobes: Fix null pointer reference in arch_prepare_kprobe()
I found a null pointer reference in arch_prepare_kprobe():
# echo 'p cmdline_proc_show' > kprobe_events # echo 'p cmdline_proc_show+16' >> kprobe_events Kernel attempted to read user page (0) - exploit attempt? (uid: 0) BUG: Kernel NULL pointer dereference on read at 0x00000000 Faulting instruction address: 0xc000000000050bfc Oops: Kernel access of bad area, sig: 11 [#1] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV Modules linked in: CPU: 0 PID: 122 Comm: sh Not tainted 6.0.0-rc3-00007-gdcf8e5633e2e #10 NIP: c000000000050bfc LR: c000000000050bec CTR: 0000000000005bdc REGS: c0000000348475b0 TRAP: 0300 Not tainted (6.0.0-rc3-00007-gdcf8e5633e2e) MSR: 9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 88002444 XER: 20040006 CFAR: c00000000022d100 DAR: 0000000000000000 DSISR: 40000000 IRQMASK: 0 ... NIP arch_prepare_kprobe+0x10c/0x2d0 LR arch_prepare_kprobe+0xfc/0x2d0 Call Trace: 0xc0000000012f77a0 (unreliable) register_kprobe+0x3c0/0x7a0 __register_trace_kprobe+0x140/0x1a0 __trace_kprobe_create+0x794/0x1040 trace_probe_create+0xc4/0xe0 create_or_delete_trace_kprobe+0x2c/0x80 trace_parse_run_command+0xf0/0x210 probes_write+0x20/0x40 vfs_write+0xfc/0x450 ksys_write+0x84/0x140 system_call_exception+0x17c/0x3a0 system_call_vectored_common+0xe8/0x278 --- interrupt: 3000 at 0x7fffa5682de0 NIP: 00007fffa5682de0 LR: 0000000000000000 CTR: 0000000000000000 REGS: c000000034847e80 TRAP: 3000 Not tainted (6.0.0-rc3-00007-gdcf8e5633e2e) MSR: 900000000280f033 <SF,HV,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 44002408 XER: 00000000
The address being probed has some special:
cmdline_proc_show: Probe based on ftrace cmdline_proc_show+16: Probe for the next instruction at the ftrace location
The ftrace-based kprobe does not generate kprobe::ainsn::insn, it gets set to NULL. In arch_prepare_kprobe() it will check for:
... prev = get_kprobe(p->addr - 1); preempt_enable_no_resched(); if (prev && ppc_inst_prefixed(ppc_inst_read(prev->ainsn.insn))) { ...
If prev is based on ftrace, 'ppc_inst_read(prev->ainsn.insn)' will occur with a null pointer reference. At this point prev->addr will not be a prefixed instruction, so the check can be skipped.
Check if prev is ftrace-based kprobe before reading 'prev->ainsn.insn' to fix this problem.
[mpe: Trim oops]
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Debian | — | Upgrade linux | Dec 10, 2025 | Dec 10, 2025 |
| Huawei Euleros 2_0_sp11 | — | Upgrade kernel-abi-stablelistsUpgrade kernelUpgrade kernel-toolsUpgrade kernel-tools-libsUpgrade bpftoolUpgrade python3-perf | Mar 17, 2026 | Mar 17, 2026 |
| Huawei Euleros 2_0_sp13 | — | Upgrade kernel-toolsUpgrade kernel-tools-libsUpgrade bpftoolUpgrade kernel-abi-stablelistsUpgrade python3-perfUpgrade kernel | Mar 10, 2026 | Mar 10, 2026 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Dec 9, 2025 |
| Ubuntu | — | Upgrade linux-oracle-5.15Upgrade linux-aws-5.15Upgrade linux-nvidiaUpgrade linux-oracleUpgrade linux-gkeUpgrade linux-lowlatencyUpgrade linux-riscv-5.15Upgrade linux-realtimeUpgrade linux-intel-iotgUpgrade linux-lowlatency-hwe-5.15Upgrade linux-raspiUpgrade linux-gcp-5.15Upgrade linux-kvmUpgrade linux-ibmUpgrade linux-bluefieldUpgrade linuxUpgrade linux-gkeopUpgrade linux-hwe-5.15Upgrade linux-intel-iotg-5.15Upgrade linux-azure-5.15Upgrade linux-awsUpgrade linux-azureUpgrade linux-gcp | Dec 11, 2025 | Dec 9, 2025 |
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