From: Behan Webster <beh...@converseincode.com>

Replaced the use of a Variable Length Array In Struct (VLAIS) with a C99
compliant equivalent. This patch allocates the appropriate amount of memory
using a char array using the SHASH_DESC_ON_STACK macro.

The new code can be compiled with both gcc and clang.

Signed-off-by: Behan Webster <beh...@converseincode.com>
Reviewed-by: Mark Charlebois <charl...@gmail.com>
Reviewed-by: Jan-Simon Möller <dl...@gmx.de>
Cc: t...@linutronix.de
---
 security/integrity/ima/ima_crypto.c | 51 +++++++++++++++++--------------------
 1 file changed, 23 insertions(+), 28 deletions(-)

diff --git a/security/integrity/ima/ima_crypto.c 
b/security/integrity/ima/ima_crypto.c
index 0bd7328..bb55737 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -380,17 +380,14 @@ static int ima_calc_file_hash_tfm(struct file *file,
        loff_t i_size, offset = 0;
        char *rbuf;
        int rc, read = 0;
-       struct {
-               struct shash_desc shash;
-               char ctx[crypto_shash_descsize(tfm)];
-       } desc;
+       SHASH_DESC_ON_STACK(shash, tfm);
 
-       desc.shash.tfm = tfm;
-       desc.shash.flags = 0;
+       shash->tfm = tfm;
+       shash->flags = 0;
 
        hash->length = crypto_shash_digestsize(tfm);
 
-       rc = crypto_shash_init(&desc.shash);
+       rc = crypto_shash_init(shash);
        if (rc != 0)
                return rc;
 
@@ -420,7 +417,7 @@ static int ima_calc_file_hash_tfm(struct file *file,
                        break;
                offset += rbuf_len;
 
-               rc = crypto_shash_update(&desc.shash, rbuf, rbuf_len);
+               rc = crypto_shash_update(shash, rbuf, rbuf_len);
                if (rc)
                        break;
        }
@@ -429,7 +426,7 @@ static int ima_calc_file_hash_tfm(struct file *file,
        kfree(rbuf);
 out:
        if (!rc)
-               rc = crypto_shash_final(&desc.shash, hash->digest);
+               rc = crypto_shash_final(shash, hash->digest);
        return rc;
 }
 
@@ -487,18 +484,17 @@ static int ima_calc_field_array_hash_tfm(struct 
ima_field_data *field_data,
                                         struct ima_digest_data *hash,
                                         struct crypto_shash *tfm)
 {
-       struct {
-               struct shash_desc shash;
-               char ctx[crypto_shash_descsize(tfm)];
-       } desc;
+       char desc[sizeof(struct shash_desc) +
+               crypto_shash_descsize(tfm)] CRYPTO_MINALIGN_ATTR;
+       struct shash_desc *shash = (struct shash_desc *)desc;
        int rc, i;
 
-       desc.shash.tfm = tfm;
-       desc.shash.flags = 0;
+       shash->tfm = tfm;
+       shash->flags = 0;
 
        hash->length = crypto_shash_digestsize(tfm);
 
-       rc = crypto_shash_init(&desc.shash);
+       rc = crypto_shash_init(shash);
        if (rc != 0)
                return rc;
 
@@ -508,7 +504,7 @@ static int ima_calc_field_array_hash_tfm(struct 
ima_field_data *field_data,
                u32 datalen = field_data[i].len;
 
                if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) {
-                       rc = crypto_shash_update(&desc.shash,
+                       rc = crypto_shash_update(shash,
                                                (const u8 *) &field_data[i].len,
                                                sizeof(field_data[i].len));
                        if (rc)
@@ -518,13 +514,13 @@ static int ima_calc_field_array_hash_tfm(struct 
ima_field_data *field_data,
                        data_to_hash = buffer;
                        datalen = IMA_EVENT_NAME_LEN_MAX + 1;
                }
-               rc = crypto_shash_update(&desc.shash, data_to_hash, datalen);
+               rc = crypto_shash_update(shash, data_to_hash, datalen);
                if (rc)
                        break;
        }
 
        if (!rc)
-               rc = crypto_shash_final(&desc.shash, hash->digest);
+               rc = crypto_shash_final(shash, hash->digest);
 
        return rc;
 }
@@ -565,15 +561,14 @@ static int __init ima_calc_boot_aggregate_tfm(char 
*digest,
 {
        u8 pcr_i[TPM_DIGEST_SIZE];
        int rc, i;
-       struct {
-               struct shash_desc shash;
-               char ctx[crypto_shash_descsize(tfm)];
-       } desc;
+       char desc[sizeof(struct shash_desc) +
+               crypto_shash_descsize(tfm)] CRYPTO_MINALIGN_ATTR;
+       struct shash_desc *shash = (struct shash_desc *)desc;
 
-       desc.shash.tfm = tfm;
-       desc.shash.flags = 0;
+       shash->tfm = tfm;
+       shash->flags = 0;
 
-       rc = crypto_shash_init(&desc.shash);
+       rc = crypto_shash_init(shash);
        if (rc != 0)
                return rc;
 
@@ -581,10 +576,10 @@ static int __init ima_calc_boot_aggregate_tfm(char 
*digest,
        for (i = TPM_PCR0; i < TPM_PCR8; i++) {
                ima_pcrread(i, pcr_i);
                /* now accumulate with current aggregate */
-               rc = crypto_shash_update(&desc.shash, pcr_i, TPM_DIGEST_SIZE);
+               rc = crypto_shash_update(shash, pcr_i, TPM_DIGEST_SIZE);
        }
        if (!rc)
-               crypto_shash_final(&desc.shash, digest);
+               crypto_shash_final(shash, digest);
        return rc;
 }
 
-- 
1.9.1

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