KEYS: DH: ensure the KDF counter is properly aligned

Accessing a 'u8[4]' through a '__be32 *' violates alignment rules.  Just
make the counter a __be32 instead.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: James Morris <james.l.morris@oracle.com>

1 files changed, 3 insertions, 13 deletions

diff --git a/security/keys/dh.c b/security/keys/dh.c
index 1c1cac677041..63ac87d430db 100644
--- a/security/keys/dh.c
+++ b/security/keys/dh.c
@@ -130,14 +130,6 @@ static void kdf_dealloc(struct kdf_sdesc *sdesc)
         kzfree(sdesc);
 }
 
-/* convert 32 bit integer into its string representation */
-static inline void crypto_kw_cpu_to_be32(u32 val, u8 *buf)
-{
-        __be32 *a = (__be32 *)buf;
-
-        *a = cpu_to_be32(val);
-}
-
 /*
  * Implementation of the KDF in counter mode according to SP800-108 section 5.1
  * as well as SP800-56A section 5.8.1 (Single-step KDF).
@@ -154,16 +146,14 @@ static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,
         unsigned int h = crypto_shash_digestsize(desc->tfm);
         int err = 0;
         u8 *dst_orig = dst;
-        u32 i = 1;
-        u8 iteration[sizeof(u32)];
+        __be32 counter = cpu_to_be32(1);
 
         while (dlen) {
                 err = crypto_shash_init(desc);
                 if (err)
                         goto err;
 
-                crypto_kw_cpu_to_be32(i, iteration);
-                err = crypto_shash_update(desc, iteration, sizeof(u32));
+                err = crypto_shash_update(desc, (u8 *)&counter, sizeof(__be32));
                 if (err)
                         goto err;
 
@@ -189,7 +179,7 @@ static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen,
 
                         dlen -= h;
                         dst += h;
-                        i++;
+                        counter = cpu_to_be32(be32_to_cpu(counter) + 1);
                 }
         }