Bug 2313122 (CVE-2024-46774)

Summary: CVE-2024-46774 kernel: powerpc/rtas: Prevent Spectre v1 gadget construction in sys_rtas()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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Bug Depends On: 2313229    
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Description OSIDB Bzimport 2024-09-18 08:22:32 UTC 
In the Linux kernel, the following vulnerability has been resolved:

powerpc/rtas: Prevent Spectre v1 gadget construction in sys_rtas()

Smatch warns:

  arch/powerpc/kernel/rtas.c:1932 __do_sys_rtas() warn: potential
  spectre issue 'args.args' [r] (local cap)

The 'nargs' and 'nret' locals come directly from a user-supplied
buffer and are used as indexes into a small stack-based array and as
inputs to copy_to_user() after they are subject to bounds checks.

Use array_index_nospec() after the bounds checks to clamp these values
for speculative execution.
Comment 1 Michal Findra 2024-09-18 11:13:56 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024091847-CVE-2024-46774-48d9@gregkh/T