[PATCH 1/1] use crc32 instead of md5 for hibernation e820 integrity check

[Chris von Recklinghausen]

Suspend fails on a system in fips mode because md5 is used for the e820
integrity check and is not available. Use crc32 instead.

Fixes: 62a03defeabd ("PM / hibernate: Verify the consistent of e820 memory map
       by md5 digest")
Signed-off-by: Chris von Recklinghausen <creck...@redhat.com>
---
 arch/x86/power/hibernate.c | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/arch/x86/power/hibernate.c b/arch/x86/power/hibernate.c
index cd3914fc9f3d..6a3f4e32e49c 100644
--- a/arch/x86/power/hibernate.c
+++ b/arch/x86/power/hibernate.c
@@ -55,31 +55,31 @@ int pfn_is_nosave(unsigned long pfn)
 }
 
 
-#define MD5_DIGEST_SIZE 16
+#define CRC32_DIGEST_SIZE 16
 
 struct restore_data_record {
        unsigned long jump_address;
        unsigned long jump_address_phys;
        unsigned long cr3;
        unsigned long magic;
-       u8 e820_digest[MD5_DIGEST_SIZE];
+       u8 e820_digest[CRC32_DIGEST_SIZE];
 };
 
-#if IS_BUILTIN(CONFIG_CRYPTO_MD5)
+#if IS_BUILTIN(CONFIG_CRYPTO_CRC32)
 /**
- * get_e820_md5 - calculate md5 according to given e820 table
+ * get_e820_crc32 - calculate crc32 according to given e820 table
  *
  * @table: the e820 table to be calculated
- * @buf: the md5 result to be stored to
+ * @buf: the crc32 result to be stored to
  */
-static int get_e820_md5(struct e820_table *table, void *buf)
+static int get_e820_crc32(struct e820_table *table, void *buf)
 {
        struct crypto_shash *tfm;
        struct shash_desc *desc;
        int size;
        int ret = 0;
 
-       tfm = crypto_alloc_shash("md5", 0, 0);
+       tfm = crypto_alloc_shash("crc32", 0, 0);
        if (IS_ERR(tfm))
                return -ENOMEM;
 
@@ -107,24 +107,24 @@ static int get_e820_md5(struct e820_table *table, void 
*buf)
 
 static int hibernation_e820_save(void *buf)
 {
-       return get_e820_md5(e820_table_firmware, buf);
+       return get_e820_crc32(e820_table_firmware, buf);
 }
 
 static bool hibernation_e820_mismatch(void *buf)
 {
        int ret;
-       u8 result[MD5_DIGEST_SIZE];
+       u8 result[CRC32_DIGEST_SIZE];
 
-       memset(result, 0, MD5_DIGEST_SIZE);
+       memset(result, 0, CRC32_DIGEST_SIZE);
        /* If there is no digest in suspend kernel, let it go. */
-       if (!memcmp(result, buf, MD5_DIGEST_SIZE))
+       if (!memcmp(result, buf, CRC32_DIGEST_SIZE))
                return false;
 
-       ret = get_e820_md5(e820_table_firmware, result);
+       ret = get_e820_crc32(e820_table_firmware, result);
        if (ret)
                return true;
 
-       return memcmp(result, buf, MD5_DIGEST_SIZE) ? true : false;
+       return memcmp(result, buf, CRC32_DIGEST_SIZE) ? true : false;
 }
 #else
 static int hibernation_e820_save(void *buf)
@@ -134,7 +134,7 @@ static int hibernation_e820_save(void *buf)
 
 static bool hibernation_e820_mismatch(void *buf)
 {
-       /* If md5 is not builtin for restore kernel, let it go. */
+       /* If crc32 is not builtin for restore kernel, let it go. */
        return false;
 }
 #endif
@@ -160,6 +160,9 @@ int arch_hibernation_header_save(void *addr, unsigned int 
max_size)
        rdr->jump_address = (unsigned long)restore_registers;
        rdr->jump_address_phys = __pa_symbol(restore_registers);
 
+       /* crc32 digest size is 4 but digest buffer size is 16 so zero it all */
+       memset(rdr->e820_digest, 0, CRC32_DIGEST_SIZE);
+
        /*
         * The restore code fixes up CR3 and CR4 in the following sequence:
         *
-- 
2.18.1