CVE-2026-98920: Linux Vulnerability

Description

In the Linux kernel, the following vulnerability has been resolved: netfs: Fix missing alloc tagging of direct mempool allocations Commit 1d78d56c43ef ("netfs: Fix folio_queue ENOMEM in writeback by adding a mempool") added a mempool for the folio_queues and made the request, subrequest and folio_queue allocations distinguish between writeback and everything else. Writeback is part of memory reclaim and must not fail due to ENOMEM, so it allocates under GFP_NOFS through mempool_alloc(), which may dip into the pool's reserve and, if that runs empty, wait for elements to be returned. The GFP_KERNEL paths, which can return -ENOMEM to their callers, invoke the pool's ->alloc() callback directly instead. The direct call, however, skips the alloc_hooks() wrapper that the mempool_alloc() macro provides. The pool callbacks, mempool_alloc_slab() and mempool_kmalloc(), call kmem_cache_alloc_noprof() and kmalloc_noprof() and rely on current->alloc_tag having been set by the caller. With CONFIG_MEM_ALLOC_PROFILING_DEBUG=y this leads to current->alloc_tag not set WARNING: ./include/linux/alloc_tag.h:161 at __alloc_tagging_slab_alloc_hook alloc_tag was not set WARNING: ./include/linux/alloc_tag.h:166 at __alloc_tagging_slab_free_hook at allocation and free time respectively, as reported when reading files on a CIFS mount. The allocations are also missing from /proc/allocinfo. Wrap the direct ->alloc() invocations in alloc_hooks() with a new mempool_alloc_noreserve() helper in include/linux/mempool.h, next to the other alloc_hooks()-wrapped macros such as mempool_alloc(). The GFP_KERNEL paths keep their failable allocation semantics, they just get tagged now.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 15ed8a9b7c63e9171f5139a6aaa1ffb61809861f, < 5c03da745171485fd181f17b69213464f6d05f3d; >= 1d78d56c43ef3768183e8370e7367b162700e049, < 37a2042748bc880df03ff8315db86ed82991fbb8; >= 1d78d56c43ef3768183e8370e7367b162700e049, < b78b728e21c32ec4c330b299f657fb1eb02dffc2; b343252d6f536203dd0660f676190dcbf6d2ecdc; 3f6d7f8a5416d852648d15a05e895f1195ee8a85; >= 6.12.114, < 6.13; >= 7.1.8, < 7.2
Linux	Linux	7.2

References

Timeline

Published: Oct 23, 2026
Last Modified: Oct 23, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-98920?

In the Linux kernel, the following vulnerability has been resolved: netfs: Fix missing alloc tagging of direct mempool allocations Commit 1d78d56c43ef ("netfs: Fix folio_queue ENOMEM in writeback by adding a mempool") added a mempool for the folio_queues and made the request, subrequest and folio_queue allocations distinguish between writeback and everything else. Writeback is part of memory reclaim and must not fail due to ENOMEM, so it allocates under GFP_NOFS through mempool_alloc(), which may dip into the pool's reserve and, if that runs empty, wait for elements to be returned. The GFP_KERNEL paths, which can return -ENOMEM to their callers, invoke the pool's ->alloc() callback directly instead. The direct call, however, skips the alloc_hooks() wrapper that the mempool_alloc() macro provides. The pool callbacks, mempool_alloc_slab() and mempool_kmalloc(), call kmem_cache_alloc_noprof() and kmalloc_noprof() and rely on current->alloc_tag having been set by the caller. With CONFIG_MEM_ALLOC_PROFILING_DEBUG=y this leads to current->alloc_tag not set WARNING: ./include/linux/alloc_tag.h:161 at __alloc_tagging_slab_alloc_hook alloc_tag was not set WARNING: ./include/linux/alloc_tag.h:166 at __alloc_tagging_slab_free_hook at allocation and free time respectively, as reported when reading files on a CIFS mount. The allocations are also missing from /proc/allocinfo. Wrap the direct ->alloc() invocations in alloc_hooks() with a new mempool_alloc_noreserve() helper in include/linux/mempool.h, next to the other alloc_hooks()-wrapped macros such as mempool_alloc(). The GFP_KERNEL paths keep their failable allocation semantics, they just get tagged now.

How severe is CVE-2026-98920?

Severity scoring for CVE-2026-98920 is pending analysis.

How do I fix CVE-2026-98920?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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