Linux Kernel Daily: PowerPC KVM Memory Safety Fixes
A batch of powerpc fixes merged by Linus Torvalds closes three distinct memory-safety holes in KVM's Book3S HV code and the IOMMU layer, all affecting POWER9/10 systems running secure or nested guests.
Duration: PT2M8S
Episode overview
This episode is a short developer briefing from Linux Kernel Daily.
It explains recent repository work in plain language.
- Show: Linux Kernel Daily
- Published: 2026-09-17T06:01:28Z
- Audio duration: PT2M8S
Transcript excerpt
This excerpt keeps the crawler page concise. Listen to the episode or use the RSS feed for the full update.
Good morning. It's September 17th, 2026, and this is Linux Kernel Daily.
Today's activity is small in volume but sharp in focus: four commits, all landing through Madhavan Srinivasan's powerpc fixes pull, and all addressing memory-safety bugs in virtualization code.
The throughline here is resource lifecycle management under concurrency. Commit 51938df fixes a use-after-free in the nested-guest tlbie emulation path — a vCPU could drop a lock, let another vCPU tear down and free a nested guest structure, and then dereference the dangling pointer. The fix borrows the get-and-put…
Commit 0a416ee addresses a parallel problem on the secure-guest side. When a page-in operation to the Ultravisor fails, the code was skipping cleanup and permanently leaking a secure device page — consuming a slot from a firmware-bounded pool for the life of the VM. The fix mirrors the existing, correct handling in…
Both of these are the same lesson in different clothing — partial-failure paths in complex locking and reference-counted resources are where bugs hide, and the fix in each case was to match a pattern that already existed correctly elsewhere in the file.
The third fix, commit 0b271f7, is more of an…
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