On Tue, Oct 21, 2025 at 2:01 AM Mike Rapoport <[email protected]> wrote: > > On Mon, Oct 20, 2025 at 08:08:49PM -0400, Pasha Tatashin wrote: > > This series fixes a memory corruption bug in KHO that occurs when KFENCE > > is enabled. > > > > The root cause is that KHO metadata, allocated via kzalloc(), can be > > randomly serviced by kfence_alloc(). When a kernel boots via KHO, the > > early memblock allocator is restricted to a "scratch area". This forces > > the KFENCE pool to be allocated within this scratch area, creating a > > conflict. If KHO metadata is subsequently placed in this pool, it gets > > corrupted during the next kexec operation. > > > > Patch 1/3 introduces a debug-only feature (CONFIG_KEXEC_HANDOVER_DEBUG) > > that adds checks to detect and fail any operation that attempts to place > > KHO metadata or preserved memory within the scratch area. This serves as > > a validation and diagnostic tool to confirm the problem without > > affecting production builds. > > > > Patch 2/3 Increases bitmap to PAGE_SIZE, so buddy allocator can be used. > > > > Patch 3/3 Provides the fix by modifying KHO to allocate its metadata > > directly from the buddy allocator instead of slab. This bypasses the > > KFENCE interception entirely. > > > > Pasha Tatashin (3): > > liveupdate: kho: warn and fail on metadata or preserved memory in > > scratch area > > liveupdate: kho: Increase metadata bitmap size to PAGE_SIZE > > liveupdate: kho: allocate metadata directly from the buddy allocator > > With liveupdate: dropped from the subjects
I noticed "liveupdate: " subject prefix left over only after sending these patches. Andrew, would you like me to resend them, or could you remove the prefix from these patches? > Reviewed-by: Mike Rapoport (Microsoft) <[email protected]> > > > include/linux/gfp.h | 3 ++ > > kernel/Kconfig.kexec | 9 ++++ > > kernel/Makefile | 1 + > > kernel/kexec_handover.c | 72 ++++++++++++++++++++------------ > > kernel/kexec_handover_debug.c | 25 +++++++++++ > > kernel/kexec_handover_internal.h | 16 +++++++ > > 6 files changed, 100 insertions(+), 26 deletions(-) > > create mode 100644 kernel/kexec_handover_debug.c > > create mode 100644 kernel/kexec_handover_internal.h > > > > > > base-commit: 6548d364a3e850326831799d7e3ea2d7bb97ba08 > > -- > > 2.51.0.869.ge66316f041-goog > > > > -- > Sincerely yours, > Mike.
