CVE - CVE-2025-22015

CVE-ID
CVE-2025-22015	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
In the Linux kernel, the following vulnerability has been resolved: mm/migrate: fix shmem xarray update during migration A shmem folio can be either in page cache or in swap cache, but not at the same time. Namely, once it is in swap cache, folio->mapping should be NULL, and the folio is no longer in a shmem mapping. In __folio_migrate_mapping(), to determine the number of xarray entries to update, folio_test_swapbacked() is used, but that conflates shmem in page cache case and shmem in swap cache case. It leads to xarray multi-index entry corruption, since it turns a sibling entry to a normal entry during xas_store() (see [1] for a userspace reproduction). Fix it by only using folio_test_swapcache() to determine whether xarray is storing swap cache entries or not to choose the right number of xarray entries to update. [1] https://lore.kernel.org/linux-mm/Z8idPCkaJW1IChjT@casper.infradead.org/ Note: In __split_huge_page(), folio_test_anon() && folio_test_swapcache() is used to get swap_cache address space, but that ignores the shmem folio in swap cache case. It could lead to NULL pointer dereferencing when a in-swap-cache shmem folio is split at __xa_store(), since !folio_test_anon() is true and folio->mapping is NULL. But fortunately, its caller split_huge_page_to_list_to_order() bails out early with EBUSY when folio->mapping is NULL. So no need to take care of it here.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/29124ae980e2860f0eec7355949d3d3292ee81da URL:https://git.kernel.org/stable/c/29124ae980e2860f0eec7355949d3d3292ee81da MISC:https://git.kernel.org/stable/c/49100c0b070e900f87c8fac3be9b9ef8a30fa673 URL:https://git.kernel.org/stable/c/49100c0b070e900f87c8fac3be9b9ef8a30fa673 MISC:https://git.kernel.org/stable/c/60cf233b585cdf1f3c5e52d1225606b86acd08b0 URL:https://git.kernel.org/stable/c/60cf233b585cdf1f3c5e52d1225606b86acd08b0 MISC:https://git.kernel.org/stable/c/75cfb92eb63298d717b6b0118f91ba12c4fcfeb5 URL:https://git.kernel.org/stable/c/75cfb92eb63298d717b6b0118f91ba12c4fcfeb5 MISC:https://git.kernel.org/stable/c/c057ee03f751d6cecf7ee64f52f6545d94082aaa URL:https://git.kernel.org/stable/c/c057ee03f751d6cecf7ee64f52f6545d94082aaa
Assigning CNA
kernel.org
Date Record Created
20241229	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20241229)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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