Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-07-25T00:00:00 kernel: mm/slab: do not limit zeroing to orig_size when only red zoning is enabled 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CWE-824

In the Linux kernel, the following vulnerability has been resolved: mm/slab: do not limit zeroing to orig_size when only red zoning is enabled When init (zeroing) on allocation is requested, for kmalloc() we generally have to zero the full object size even if a smaller size is requested, in order to provide krealloc()'s __GFP_ZERO guarantees. But if we track the requested size, krealloc() uses that information to do the right thing, so we can zero only the requested size. With red zoning also enabled, any extra size became part of the red zone, so it must not be zeroed and thus we must zero only the requested size. However the current check is imprecise, and will trigger also when only SLAB_RED_ZONE is enabled without SLAB_STORE_USER (which enables tracking the requested size). This means enabling red zoning alone can compromise krealloc()'s __GFP_ZERO contract. Fix this by using slub_debug_orig_size() instead, which is the exact check for whether the requested size is tracked. We don't need to care if red zoning is also enabled or not. Also update and expand the comment accordingly.

A flaw was found in the Linux kernel's memory management subsystem. This issue occurs when the kernel's memory allocator attempts to zero out newly allocated memory, but an incorrect check prevents the full memory region from being cleared under specific configurations. This can lead to memory not being fully zeroed as intended, potentially allowing a local attacker to access sensitive information from previously used memory regions.

Red Hat Enterprise Linux 10 2026-08-11T00:00:00Z RHSA-2026:53330 kernel-0:6.12.0-211.46.1.el10_2 Red Hat Enterprise Linux 9 2026-08-11T00:00:00Z RHSA-2026:53329 kernel-0:5.14.0-687.38.1.el9_8 Red Hat Enterprise Linux 9 2026-08-11T00:00:00Z RHSA-2026:53329 kernel-0:5.14.0-687.38.1.el9_8 Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Not affected kernel Red Hat Enterprise Linux 8 Not affected kernel-rt Red Hat Enterprise Linux 9 Fix deferred kernel-rt Red Hat Hardened Images Not affected erlang27 https://www.cve.org/CVERecord?id=CVE-2026-64368 https://nvd.nist.gov/vuln/detail/CVE-2026-64368 https://lore.kernel.org/linux-cve-announce/2026072522-CVE-2026-64368-014f@gregkh/T