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SubjectRe: potential null pointer dereference in setup_cpuid_table
On Thu, Jul 27, 2023 at 03:22:42PM +0100, Colin King (gmail) wrote:
> Hi,
>
> Static analysis with cppcheck found a potential null pointer dereference in
> function setup_cpuid_table in arch/x86/kernel/sev-shared.c as follows:
>
> if (!cc_info || !cc_info->cpuid_phys || cc_info->cpuid_len <
> PAGE_SIZE)
> sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID);
>
> cpuid_table_fw = (const struct snp_cpuid_table
> *)cc_info->cpuid_phys;
>
>
> cc_info is being null checked, so it's potentially null,

You mean, it is not null if the check passes?

> however, the assignment to cpuid_table_fw is dereferencing cc_info.
> Either cc_info is never null and the null check is redundant, or there
> is a potential null pointer dereference.

I'm not sure what you're asking. It is checked for !NULL in the if
clause.

Or are you missing the fact that sev_es_terminate() actually terminates
the guest so that if it is NULL, it won't ever be dereferenced?

Or am I missing something?

Thx.

--
Regards/Gruss,
Boris.

https://people.kernel.org/tglx/notes-about-netiquette

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