crypto: pkcs7 - Fix unaligned access in pkcs7_verify()

On sparc, we see unaligned access messages on each modprobe[-r]:

Kernel unaligned access at TPC[6ad9b4] pkcs7_verify [..]
Kernel unaligned access at TPC[6a5484] crypto_shash_finup [..]
Kernel unaligned access at TPC[6a5390] crypto_shash_update [..]
Kernel unaligned access at TPC[10150308] sha1_sparc64_update [..]
Kernel unaligned access at TPC[101501ac] __sha1_sparc64_update [..]

These ware triggered by mod_verify_sig() invocations of pkcs_verify(), and
are are being caused by an unaligned desc at (sha1, digest_size is 0x14)
        desc = digest + digest_size;

To fix this, pkcs7_verify needs to make sure that desc is pointing
at an aligned value past the digest_size, and kzalloc appropriately,
taking alignment values into consideration.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 3 insertions, 2 deletions

diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c
index d20c0b4b880e..325575caf6b4 100644
--- a/crypto/asymmetric_keys/pkcs7_verify.c
+++ b/crypto/asymmetric_keys/pkcs7_verify.c
@@ -49,11 +49,12 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7,
         sinfo->sig.digest_size = digest_size = crypto_shash_digestsize(tfm);
 
         ret = -ENOMEM;
-        digest = kzalloc(digest_size + desc_size, GFP_KERNEL);
+        digest = kzalloc(ALIGN(digest_size, __alignof__(*desc)) + desc_size,
+                         GFP_KERNEL);
         if (!digest)
                 goto error_no_desc;
 
-        desc = digest + digest_size;
+        desc = PTR_ALIGN(digest + digest_size, __alignof__(*desc));
         desc->tfm   = tfm;
         desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;