Bug 2532049 (CVE-2026-81016)

Summary: CVE-2026-81016 kernel: platform/x86/amd/pmc: Propagate SMU errors and validate S2D address
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel. Specifically, within the AMD Platform Management Controller (PMC) component, the `amd_stb_s2d_init()` function does not properly validate memory addresses returned by System Management Unit (SMU) commands. This can result in the kernel attempting to map a critical memory region at address zero, leading to system warnings and potential instability. This issue could be exploited by a local attacker to cause a denial of service.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-11 20:18:23 UTC 
In the Linux kernel, the following vulnerability has been resolved:

platform/x86/amd/pmc: Propagate SMU errors and validate S2D address

amd_stb_s2d_init() discards the return value of several S2D SMU commands.
When the SMU refuses a command (e.g. "SMU cmd failed. err: 0xff") the
failure is only noticed indirectly - if at all - and reported as -EIO,
masking the real error.

More seriously, the S2D_PHYS_ADDR_LOW/HIGH return values are ignored, so
on failure phys_addr_low/hi are left uninitialised and the assembled
address is passed straight to devm_ioremap().  When the SMU leaves them at
zero this maps physical address 0 and trips the ioremap-on-RAM warning:

  amd_pmc AMDI000B:00: SMU cmd failed. err: 0xff
  ioremap on RAM at 0x0000000000000000 - 0x0000000000ffffff
  WARNING: CPU: 13 PID: 4592 at arch/x86/mm/ioremap.c:...

Check the return value of each SMU command and propagate it, and reject a
zero physical address before calling devm_ioremap().
Comment 1 Mauro Matteo Cascella 2026-09-14 16:28:25 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-81016.mbox