Description
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]
Metrics
No CVSS score has been published yet.
Affected software
No affected versions have been published.
Timeline
- Published
- Dec 30, 2025
- Last modified
- Jun 17, 2026
- NVD status
- Deferred