CVE-2026-89718

In the Linux kernel, the following vulnerability has been resolved:

zram: fix out-of-bounds access in writeback store()

Patch series "zram: fix stale scan bounds after reinitialization".

Both writeback store() and read block state() derive their table scan bounds from zram->disksize before acquiring dev lock. If the device is reset and reinitialized with a smaller disksize between that read and lock acquisition, the bound can describe the old table while the scan operates on the new one. This can lead to out-of-bounds slot accesses.

Move both bound calculations under dev lock so each bound remains consistent with the table throughout its scan. Keep the fixes separate because the affected interfaces originate from different commits and can be backported independently.

This patch (of 2):

writeback store() calculates the table scan bounds before taking dev lock. A reset followed by reconfiguration with a smaller disksize can therefore replace zram->table while writeback store() is waiting for the lock. Once it acquires the lock, it sees an initialized device but scans the new table using the old upper bound, resulting in an out-of-bounds access.

Calculate the number of pages while holding dev lock so the scan bound matches the table protected by the lock.