[CRYPTO] Fix boundary check in standard multi-block cipher processors

The boundary check in the standard multi-block cipher processors are
broken when nbytes is not a multiple of bsize.  In those cases it will
always process an extra block.

This patch corrects the check so that it processes at most nbytes of
data.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 3 deletions

diff --git a/crypto/cipher.c b/crypto/cipher.c
index 3df47f93c9db..dfd4bcfc5975 100644
--- a/crypto/cipher.c
+++ b/crypto/cipher.c
@@ -191,6 +191,8 @@ static unsigned int cbc_process_encrypt(const struct cipher_desc *desc,
         u8 *iv = desc->info;
         unsigned int done = 0;
 
+        nbytes -= bsize;
+
         do {
                 xor(iv, src);
                 fn(crypto_tfm_ctx(tfm), dst, iv);
@@ -198,7 +200,7 @@ static unsigned int cbc_process_encrypt(const struct cipher_desc *desc,
 
                 src += bsize;
                 dst += bsize;
-        } while ((done += bsize) < nbytes);
+        } while ((done += bsize) <= nbytes);
 
         return done;
 }
@@ -219,6 +221,8 @@ static unsigned int cbc_process_decrypt(const struct cipher_desc *desc,
         u8 *iv = desc->info;
         unsigned int done = 0;
 
+        nbytes -= bsize;
+
         do {
                 u8 *tmp_dst = *dst_p;
 
@@ -230,7 +234,7 @@ static unsigned int cbc_process_decrypt(const struct cipher_desc *desc,
 
                 src += bsize;
                 dst += bsize;
-        } while ((done += bsize) < nbytes);
+        } while ((done += bsize) <= nbytes);
 
         return done;
 }
@@ -243,12 +247,14 @@ static unsigned int ecb_process(const struct cipher_desc *desc, u8 *dst,
         void (*fn)(void *, u8 *, const u8 *) = desc->crfn;
         unsigned int done = 0;
 
+        nbytes -= bsize;
+
         do {
                 fn(crypto_tfm_ctx(tfm), dst, src);
 
                 src += bsize;
                 dst += bsize;
-        } while ((done += bsize) < nbytes);
+        } while ((done += bsize) <= nbytes);
 
         return done;
 }