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    Subject[PATCH 4.9 068/118] crypto: pcbc - remove bogus memcpy()s with src == dest
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Eric Biggers <ebiggers@google.com>

    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>
    ---
    crypto/pcbc.c | 14 ++++----------
    1 file changed, 4 insertions(+), 10 deletions(-)

    --- a/crypto/pcbc.c
    +++ b/crypto/pcbc.c
    @@ -52,7 +52,7 @@ static int crypto_pcbc_encrypt_segment(s
    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);
    @@ -76,7 +76,7 @@ static int crypto_pcbc_encrypt_inplace(s
    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 {
    @@ -89,8 +89,6 @@ static int crypto_pcbc_encrypt_inplace(s
    src += bsize;
    } while ((nbytes -= bsize) >= bsize);

    - memcpy(walk->iv, iv, bsize);
    -
    return nbytes;
    }

    @@ -130,7 +128,7 @@ static int crypto_pcbc_decrypt_segment(s
    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 {
    fn(crypto_cipher_tfm(tfm), dst, src);
    @@ -142,8 +140,6 @@ static int crypto_pcbc_decrypt_segment(s
    dst += bsize;
    } while ((nbytes -= bsize) >= bsize);

    - memcpy(walk->iv, iv, bsize);
    -
    return nbytes;
    }

    @@ -156,7 +152,7 @@ static int crypto_pcbc_decrypt_inplace(s
    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 {
    @@ -169,8 +165,6 @@ static int crypto_pcbc_decrypt_inplace(s
    src += bsize;
    } while ((nbytes -= bsize) >= bsize);

    - memcpy(walk->iv, iv, bsize);
    -
    return nbytes;
    }


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