linux-kernel - Re: [PATCH] x86/sgx: fix uninitialized 'nid' variable

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Message-ID: <YFQ439+k/2zkdSb5@kernel.org>
Date:   Fri, 19 Mar 2021 07:38:39 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     linux-kernel@...r.kernel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        linux-sgx@...r.kernel.org
Subject: Re: [PATCH] x86/sgx: fix uninitialized 'nid' variable

On Thu, Mar 18, 2021 at 02:49:33PM -0700, Dave Hansen wrote:
> The NUMA fallback in __sgx_alloc_epc_page() recently grew an
> additional 'nid' variable to prevent extra trips through the
> fallback loop in case where the thread is migrated around.
> 
> But, the new copy is not properly initialized.  Fix it.
> 
> This was found by some fancy clang that 0day runs.  My gcc
> does not detect it.
> 
> Fixes: 5b8719504e3a ("x86/sgx: Add a basic NUMA allocation scheme to sgx_alloc_epc_page()")
> Reported-by: kernel test robot <lkp@...el.com>
> Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
> Cc: Jarkko Sakkinen <jarkko@...nel.org>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: x86@...nel.org
> Cc: linux-sgx@...r.kernel.org


Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>

> ---
>  arch/x86/kernel/cpu/sgx/main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index 2a0031e4a4dc..1b4d8a0e0915 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -489,7 +489,7 @@ struct sgx_epc_page *__sgx_alloc_epc_page(void)
>  {
>  	struct sgx_epc_page *page;
>  	int nid_of_current = numa_node_id();
> -	int nid;
> +	int nid = nid_of_current;
>  
>  	if (node_isset(nid_of_current, sgx_numa_mask)) {
>  		page = __sgx_alloc_epc_page_from_node(nid_of_current);
> -- 
> 2.19.1
> 
> 

/Jarkko