Linux Kernel Daily: NFS Security and Memory Management Fixes

Transcript

Good morning. This is Linux Kernel Daily for May 27th, 2026.

Today we saw three significant merge commits from Linus Torvalds addressing critical fixes across multiple subsystems.

First, Torvalds merged NFS daemon fixes from Chuck Lever's tree, targeting both regressions and stable issues. The update tightens bounds checking for sunrpc cache hash tables to prevent out-of-bounds reads, removes sensitive key material from ftrace logs, and fixes lockd's implementation of the NLM TEST procedure when permissions aren't fully available. Eight files were modified across the NFS and sunrpc codebases.

The second merge pulled thirteen hotfixes from Andrew Morton's memory management tree. Nine of these target the MM subsystem, with nine marked for stable backporting. Notable changes include reverting a problematic page pool implementation, fixing a vmalloc BUG trigger in bottom-half disabled contexts, and addressing a use-after-free in zram's writeback functionality. The update also includes maintainer email changes and fixes a critical pgtable leak in device migration.

Finally, Torvalds merged a KUnit fix from Shuah Khan addressing a serious use-after-free vulnerability in debugfs when using kunit.filter. The bug caused fatal hardware exceptions on CHERI RISC-V architectures and silent memory corruption on others. The fix couples filtered suite memory allocation lifetime to the kunit subsystem itself, transferring ownership to a global tracker that's properly cleaned up during module teardown.

What's next: These fixes should stabilize NFS operations and resolve the memory corruption issues affecting testing frameworks. Watch for additional stable backports as these fixes propagate to older kernel versions.

That's your kernel update for today. I'm your host, and we'll be back tomorrow with more development news.