linux-kernel - Re: [PATCH] KVM: SVM: snp_alloc_firmware

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Message-ID: <8050badb-8671-400f-8bb6-04255c761ba0@amd.com>
Date: Fri, 14 Feb 2025 08:53:03 -0600
From: Tom Lendacky <thomas.lendacky@....com>
To: Alexey Kardashevskiy <aik@....com>, linux-crypto@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, Ashish Kalra <ashish.kalra@....com>
Subject: Re: [PATCH] KVM: SVM: snp_alloc_firmware_pages: memory leak

On 2/13/25 21:59, Alexey Kardashevskiy wrote:
> Failure to rmpupdate leads to page(s) leak, fix that.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@....com>
> ---
>  drivers/crypto/ccp/sev-dev.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index 2e87ca0e292a..0b5f8ab657c5 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -443,8 +443,10 @@ static struct page *__snp_alloc_firmware_pages(gfp_t gfp_mask, int order)
>  		return page;
>  
>  	paddr = __pa((unsigned long)page_address(page));
> -	if (rmp_mark_pages_firmware(paddr, npages, false))
> +	if (rmp_mark_pages_firmware(paddr, npages, false)) {
> +		__free_pages(page, order);

I'm not sure we can do this. On error, rmp_mark_pages_firmware() attempts
to cleanup and restore any pages that were marked firmware. But
snp_reclaim_pages() will leak pages that it can't restore and we don't
pass back any info to the caller of rmp_mark_pages_firmware() to let it
know what pages are truly available to free.

Thanks,
Tom

>  		return NULL;
> +	}
>  
>  	return page;
>  }