Bug 2348273 (CVE-2022-49355)

Summary: CVE-2022-49355 kernel: xen: unexport __init-annotated xen_xlate_map_ballooned_pages()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerability-draftAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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[REJECTED CVE] A vulnerability was identified in the Linux kernel’s Xen subsystem, where the __init-annotated function xen_xlate_map_ballooned_pages() was incorrectly exported using EXPORT_SYMBOL, leading to the risk of kernel panics if modules accessed this freed function after system initialization. An attacker could potentially exploit this by loading a malicious module referencing the freed symbol, causing a system crash.
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Description OSIDB Bzimport 2025-02-26 03:23:42 UTC 
In the Linux kernel, the following vulnerability has been resolved:

xen: unexport __init-annotated xen_xlate_map_ballooned_pages()

EXPORT_SYMBOL and __init is a bad combination because the .init.text
section is freed up after the initialization. Hence, modules cannot
use symbols annotated __init. The access to a freed symbol may end up
with kernel panic.

modpost used to detect it, but it has been broken for a decade.

Recently, I fixed modpost so it started to warn it again, then this
showed up in linux-next builds.

There are two ways to fix it:

  - Remove __init
  - Remove EXPORT_SYMBOL

I chose the latter for this case because none of the in-tree call-sites
(arch/arm/xen/enlighten.c, arch/x86/xen/grant-table.c) is compiled as
modular.
Comment 1 Avinash Hanwate 2025-02-26 11:15:28 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025022643-CVE-2022-49355-69f7@gregkh/T
Comment 5 Avinash Hanwate 2025-02-26 15:45:49 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025022643-CVE-2022-49355-69f7@gregkh/T
Comment 8 TEJ RATHI 2025-05-16 05:47:59 UTC 
This CVE has been rejected upstream: https://lore.kernel.org/linux-cve-announce/2025022628-REJECTED-7e9e@gregkh/