crypto: pcbc - remove bogus memcpy()s with src == dest

The memcpy()s in the PCBC implementation use walk->iv as both the source
and destination, which has undefined behavior.  These memcpy()'s are
actually unneeded, because walk->iv is already used to hold the previous
plaintext block XOR'd with the previous ciphertext block.  Thus,
walk->iv is already updated to its final value.

So remove the broken and unnecessary memcpy()s.

Fixes: 91652be5d1b9 ("[CRYPTO] pcbc: Add Propagated CBC template")
Cc: <stable@vger.kernel.org> # v2.6.21+
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 4 insertions, 10 deletions

diff --git a/crypto/pcbc.c b/crypto/pcbc.c
index 8aa10144407c..1b182dfedc94 100644
--- a/crypto/pcbc.c
+++ b/crypto/pcbc.c
@@ -51,7 +51,7 @@ static int crypto_pcbc_encrypt_segment(struct skcipher_request *req,
         unsigned int nbytes = walk->nbytes;
         u8 *src = walk->src.virt.addr;
         u8 *dst = walk->dst.virt.addr;
-        u8 *iv = walk->iv;
+        u8 * const iv = walk->iv;
 
         do {
                 crypto_xor(iv, src, bsize);
@@ -72,7 +72,7 @@ static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req,
         int bsize = crypto_cipher_blocksize(tfm);
         unsigned int nbytes = walk->nbytes;
         u8 *src = walk->src.virt.addr;
-        u8 *iv = walk->iv;
+        u8 * const iv = walk->iv;
         u8 tmpbuf[MAX_CIPHER_BLOCKSIZE];
 
         do {
@@ -84,8 +84,6 @@ static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req,
                 src += bsize;
         } while ((nbytes -= bsize) >= bsize);
 
-        memcpy(walk->iv, iv, bsize);
-
         return nbytes;
 }
 
@@ -121,7 +119,7 @@ static int crypto_pcbc_decrypt_segment(struct skcipher_request *req,
         unsigned int nbytes = walk->nbytes;
         u8 *src = walk->src.virt.addr;
         u8 *dst = walk->dst.virt.addr;
-        u8 *iv = walk->iv;
+        u8 * const iv = walk->iv;
 
         do {
                 crypto_cipher_decrypt_one(tfm, dst, src);
@@ -132,8 +130,6 @@ static int crypto_pcbc_decrypt_segment(struct skcipher_request *req,
                 dst += bsize;
         } while ((nbytes -= bsize) >= bsize);
 
-        memcpy(walk->iv, iv, bsize);
-
         return nbytes;
 }
 
@@ -144,7 +140,7 @@ static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,
         int bsize = crypto_cipher_blocksize(tfm);
         unsigned int nbytes = walk->nbytes;
         u8 *src = walk->src.virt.addr;
-        u8 *iv = walk->iv;
+        u8 * const iv = walk->iv;
         u8 tmpbuf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(u32));
 
         do {
@@ -156,8 +152,6 @@ static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,
                 src += bsize;
         } while ((nbytes -= bsize) >= bsize);
 
-        memcpy(walk->iv, iv, bsize);
-
         return nbytes;
 }