Bug 2482132 (CVE-2026-45884)

Summary: CVE-2026-45884 kernel: apparmor: avoid per-cpu hold underflow in aa_get_buffer
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's AppArmor module. A local attacker could exploit an integer underflow vulnerability in the `aa_get_buffer()` function. This flaw prevents buffers from being returned to the global list, potentially leading to resource exhaustion and a Denial of Service (DoS) condition for other central processing units (CPUs).
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Description OSIDB Bzimport 2026-05-27 15:12:51 UTC 
In the Linux kernel, the following vulnerability has been resolved:

apparmor: avoid per-cpu hold underflow in aa_get_buffer

When aa_get_buffer() pulls from the per-cpu list it unconditionally
decrements cache->hold. If hold reaches 0 while count is still non-zero,
the unsigned decrement wraps to UINT_MAX. This keeps hold non-zero for a
very long time, so aa_put_buffer() never returns buffers to the global
list, which can starve other CPUs and force repeated kmalloc(aa_g_path_max)
allocations.

Guard the decrement so hold never underflows.
Comment 1 Keith Grant 2026-05-28 03:11:33 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026052716-CVE-2026-45884-441d@gregkh/T