CVE-2026-89760

Status: UPDATED  |  Advisory ID: CVE-2026-89760

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

mm, swap: don't free a hibernation slot that is in the swap cache

A slot with a folio in the swap cache is freed when the folio leaves the

cache, not when its count drops. swap_put_entries_cluster() follows that

rule. swap_free_hibernation_slot() does not, it calls

__swap_cluster_free_entries() whether or not a folio sits on the slot.

Cluster readahead can put one there. It walks a raw page_cluster sized

window of offsets around the faulting entry, and a hibernation slot passes

__swap_cache_add_check() because it is not a folio and its count is not

zero. Freeing the slot then clears the entry under that folio.

The folio is now unreachable from the swap table, and the offset goes back

to the allocator. The folio is still on the LRU though, so reclaim can

pick it up later. It then takes the old offset out of folio->swap and

overwrites the table entry there, which by then may belong to someone

else.

This bug can trigger silent memory corruption, process crashes, or data

instability across completely unrelated userspace applications - typically

occurring when uswsusp is preparing the hibernation image.

I found this while working on giving hibernation slots their own marker in

the swap table, which I had discussed with Kairui.

(https://lore.kernel.org/linux-mm/abp7aDgYLrxF3Me8@KASONG-MC4/) As far as

I know there are no reports, so there is no Reported-by/Closes to add.

Check for a cached folio before freeing. The slot is then left in the

ordinary state where only the swap cache holds it, and it is freed when

the folio leaves the cache, either through the reclaim below or through

normal reclaim later. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References