In the Linux kernel, the following vulnerability has been resolved:
powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT
lppaca_shared_proc() takes a pointer to the lppaca which is typically accessed through get_lppaca(). With DEBUG_PREEMPT enabled, this leads to checking if preemption is enabled, for example:
BUG: using smp_processor_id() in preemptible [00000000] code: grep/10693 caller is lparcfg_data+0x408/0x19a0 CPU: 4 PID: 10693 Comm: grep Not tainted 6.5.0-rc3 #2 Call Trace: dump_stack_lvl+0x154/0x200 (unreliable) check_preemption_disabled+0x214/0x220 lparcfg_data+0x408/0x19a0 ...
This isn't actually a problem however, as it does not matter which lppaca is accessed, the shared proc state will be the same. vcpudispatch_stats_procfs_init() already works around this by disabling preemption, but the lparcfg code does not, erroring any time /proc/powerpc/lparcfg is accessed with DEBUG_PREEMPT enabled.
Instead of disabling preemption on the caller side, rework lppaca_shared_proc() to not take a pointer and instead directly access the lppaca, bypassing any potential preemption checks.
[mpe: Rework to avoid needing a definition in paca.h and lppaca.h]
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Debian | — | Upgrade linux | Dec 31, 2025 | Dec 31, 2025 |
| Redhat_linux | — | No solution exists | Jul 17, 2026 | Dec 30, 2025 |
| Ubuntu | — | Upgrade linux-gcp-fipsUpgrade linux-hwe-5.15Upgrade linux-lowlatencyUpgrade linux-gkeopUpgrade linuxUpgrade linux-azure-5.15Upgrade linux-nvidia-tegra-igxUpgrade linux-raspiUpgrade linux-nvidia-tegraUpgrade linux-oracle-5.15Upgrade linux-awsUpgrade linux-nvidia-tegra-5.15Upgrade linux-aws-fipsUpgrade linux-ibmUpgrade linux-intel-iot-realtimeUpgrade linux-aws-5.15Upgrade linux-oracleUpgrade linux-realtimeUpgrade linux-intel-iotg-5.15Upgrade linux-ibm-5.15Upgrade linux-nvidiaUpgrade linux-lowlatency-hwe-5.15Upgrade linux-gkeUpgrade linux-gcpUpgrade linux-gcp-5.15Upgrade linux-intel-iotgUpgrade linux-bluefieldUpgrade linux-kvmUpgrade linux-azureUpgrade linux-xilinx-zynqmpUpgrade linux-riscv-5.15Upgrade linux-fips | Jan 6, 2026 | Jan 2, 2026 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | May 27, 2026 | Dec 30, 2025 |
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