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

BugLink: https://bugs.launchpad.net/bugs/1837952
commit 251b7aea34ba3c4d4fdfa9447695642eb8b8b098 upstream.

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>
Signed-off-by: Maxim Zhukov <mussitantesmortem@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/crypto/pcbc.c b/crypto/pcbc.c
index d9e45a9587201d7760084bd81a024c11d743dc75..67009a532201732b0dc86f9b5949a2b454b5384c 100644 (file)
--- a/crypto/pcbc.c
+++ b/crypto/pcbc.c
@@ -50,7 +50,7 @@ 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);
@@ -71,7 +71,7 @@ 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[bsize];
 
        do {
@@ -83,8 +83,6 @@ static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req,
                src += bsize;
        } while ((nbytes -= bsize) >= bsize);
 
-       memcpy(walk->iv, iv, bsize);
-
        return nbytes;
 }
 
@@ -120,7 +118,7 @@ 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);
@@ -131,8 +129,6 @@ static int crypto_pcbc_decrypt_segment(struct skcipher_request *req,
                dst += bsize;
        } while ((nbytes -= bsize) >= bsize);
 
-       memcpy(walk->iv, iv, bsize);
-
        return nbytes;
 }
 
@@ -143,7 +139,7 @@ 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[bsize] __aligned(__alignof__(u32));
 
        do {
@@ -155,8 +151,6 @@ static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,
                src += bsize;
        } while ((nbytes -= bsize) >= bsize);
 
-       memcpy(walk->iv, iv, bsize);
-
        return nbytes;
 }