On Thu, Dec 18, 2025 at 7:23 PM Pasha Tatashin <[email protected]> wrote: > > If the previous kernel enabled KHO but did not call kho_finalize() > (e.g., CONFIG_LIVEUPDATE=n or userspace skipped the finalization step), > the 'preserved-memory-map' property in the FDT remains empty/zero. > > Previously, kho_populate() would succeed regardless of the memory map's > state, reserving the incoming scratch regions in memblock. However, > kho_memory_init() would later fail to deserialize the empty map. By that > time, the scratch regions were already registered, leading to partial > initialization and subsequent list corruption (double-free) during > kho_init(). > > Move the validation of the preserved memory map earlier into > kho_populate(). If the memory map is empty/NULL: > 1. Abort kho_populate() immediately with -ENOENT. > 2. Do not register or reserve the incoming scratch memory, allowing the new > kernel to reclaim those pages as standard free memory. > 3. Leave the global 'kho_in' state uninitialized. > > Consequently, kho_memory_init() sees no active KHO context > (kho_in.mem_chunks is NULL) and falls back to kho_reserve_scratch(), > allocating fresh scratch memory as if it were a standard cold boot. > > Fixes: de51999e687c ("kho: allow memory preservation state updates after > finalization") > Reported-by: Ricardo <[email protected]> > Closes: > https://lore.kernel.org/all/[email protected] > Signed-off-by: Pasha Tatashin <[email protected]> > --- > kernel/liveupdate/kexec_handover.c | 36 +++++++++++++++++------------- > 1 file changed, 21 insertions(+), 15 deletions(-) > > diff --git a/kernel/liveupdate/kexec_handover.c > b/kernel/liveupdate/kexec_handover.c > index 9dc51fab604f..96c708f753d4 100644 > --- a/kernel/liveupdate/kexec_handover.c > +++ b/kernel/liveupdate/kexec_handover.c > @@ -460,10 +460,9 @@ static void __init deserialize_bitmap(unsigned int order, > } > } > > -/* Return true if memory was deserizlied */ > -static bool __init kho_mem_deserialize(const void *fdt) > +/* Returns head of preserved physical memory chunks pointer from FDT */ > +static struct khoser_mem_chunk * __init kho_get_mem_chunks(const void *fdt) > { > - struct khoser_mem_chunk *chunk; > const void *mem_ptr; > u64 mem; > int len; > @@ -471,16 +470,16 @@ static bool __init kho_mem_deserialize(const void *fdt) > mem_ptr = fdt_getprop(fdt, 0, PROP_PRESERVED_MEMORY_MAP, &len); > if (!mem_ptr || len != sizeof(u64)) { > pr_err("failed to get preserved memory bitmaps\n"); > - return false; > + return NULL; > } > > mem = get_unaligned((const u64 *)mem_ptr); > - chunk = mem ? phys_to_virt(mem) : NULL; > > - /* No preserved physical pages were passed, no deserialization */ > - if (!chunk) > - return false; > + return mem ? phys_to_virt(mem) : NULL;
I need to update this patch, phys_to_virt() should not be called from kho_populate() before KASLR is initialized. This causes a problem with my live update test. I will send a new version soon. Pasha
