linux-kernel - Re: [PATCH v7 1/1] use crc32 instead of md5 for hibernation e820 integrity check

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Message-ID: <YHX79XWnwaAGFtxq@sol.localdomain>
Date:   Tue, 13 Apr 2021 13:15:49 -0700
From:   Eric Biggers <ebiggers@...nel.org>
To:     Chris von Recklinghausen <crecklin@...hat.com>
Cc:     ardb@...nel.org, simo@...hat.com, rafael@...nel.org,
        decui@...rosoft.com, linux-pm@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 1/1] use crc32 instead of md5 for hibernation e820
 integrity check

On Tue, Apr 13, 2021 at 12:13:30PM -0400, Chris von Recklinghausen wrote:
> +static inline void get_e820_crc32(struct e820_table *table, void *buf)
>  {

This should just return the CRC-32 value as a u32.  There's no need for the
'void *buf' argument.

Also like I said, compute_e820_crc32() would be a more logical name.

> @@ -179,7 +133,8 @@ int arch_hibernation_header_save(void *addr, unsigned int max_size)
>  	 */
>  	rdr->cr3 = restore_cr3 & ~CR3_PCID_MASK;
>  
> -	return hibernation_e820_save(rdr->e820_digest);
> +	hibernation_e820_save(&rdr->e820_digest);
> +	return 0;

Like I said, hibernation_e820_save() should just be inlined into here:

	rdr->e820_digest = compute_e820_crc32(e820_table_firmware)

Having the helper function doesn't add anything.

>  /**
> @@ -200,7 +155,7 @@ int arch_hibernation_header_restore(void *addr)
>  	jump_address_phys = rdr->jump_address_phys;
>  	restore_cr3 = rdr->cr3;
>  
> -	if (hibernation_e820_mismatch(rdr->e820_digest)) {
> +	if (hibernation_e820_mismatch(&rdr->e820_digest)) {

Likewise, this should be just

	if (rdr->e820_digest != compute_e820_crc32(e820_table_firmware)) {

- Eric