Linux Kernel: ZRAM Slot Lock Bit Misplacement on BE64 (CVE-2026-90043)
CVE-2026-90043 Published on September 16, 2026
zram: fix slot lock bit position on big-endian 64-bit
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.
Products Associated with CVE-2026-90043
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Affected Versions
Linux:- Version 2e8ff2f51dde73a26b94aed2df4827177bd25e6e and below 052b6b2d5fe97547bd2cdb73fa894f6cfea68b11 is affected.
- Version 2e8ff2f51dde73a26b94aed2df4827177bd25e6e and below a8b5875741d416703e19ad8eeac6fce8a12bd6e4 is affected.
- Version 7.0 is affected.
- Before 7.0 is unaffected.
- Version 7.2.5, <= 7.2.* is unaffected.
- Version 7.3-rc1, <= * is unaffected.