In the Linux kernel, the following vulnerability has been resolved:
zram: fix slot lock bit position on big-endian 64-bit
The slot lock is a bit operation on the whole __lock word, which flags and
ac_time alias as two u32s. On little-endian the lock bit lands in the
position ZRAM_ENTRY_LOCK reserves in flags, so the aliasing works out. On
64-bit big-endian it lands in ac_time instead: with
ZRAM_TRACK_ENTRY_ACTIME enabled, storing the access time from
mark_slot_accessed() or slot_free() wipes out the held lock bit, letting
another CPU take the same slot lock; an access time value with that bit
set makes the slot look locked forever.
Shift the lock bit into the flags half of the word on big-endian 64-bit.
