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    Subject[PATCH v2 4/6] net-PPP: Less function calls in mppe_alloc() after error detection
    From: Markus Elfring <elfring@users.sourceforge.net>
    Date: Thu, 4 Dec 2014 22:30:20 +0100

    The functions crypto_free_blkcipher((), crypto_free_hash() and kfree() could be
    called in some cases by the mppe_alloc() function during error handling even
    if the passed data structure element contained still a null pointer.

    This implementation detail could be improved by adjustments for jump labels.

    Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
    ---
    drivers/net/ppp/ppp_mppe.c | 20 +++++++++-----------
    1 file changed, 9 insertions(+), 11 deletions(-)

    diff --git a/drivers/net/ppp/ppp_mppe.c b/drivers/net/ppp/ppp_mppe.c
    index 94ff216..c82198f 100644
    --- a/drivers/net/ppp/ppp_mppe.c
    +++ b/drivers/net/ppp/ppp_mppe.c
    @@ -196,11 +196,11 @@ static void *mppe_alloc(unsigned char *options, int optlen)

    if (optlen != CILEN_MPPE + sizeof(state->master_key) ||
    options[0] != CI_MPPE || options[1] != CILEN_MPPE)
    - goto out;
    + return NULL;

    state = kzalloc(sizeof(*state), GFP_KERNEL);
    if (state == NULL)
    - goto out;
    + return NULL;


    state->arc4 = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
    @@ -212,16 +212,16 @@ static void *mppe_alloc(unsigned char *options, int optlen)
    state->sha1 = crypto_alloc_hash("sha1", 0, CRYPTO_ALG_ASYNC);
    if (IS_ERR(state->sha1)) {
    state->sha1 = NULL;
    - goto out_free;
    + goto out_free_blkcipher;
    }

    digestsize = crypto_hash_digestsize(state->sha1);
    if (digestsize < MPPE_MAX_KEY_LEN)
    - goto out_free;
    + goto out_free_hash;

    state->sha1_digest = kmalloc(digestsize, GFP_KERNEL);
    if (!state->sha1_digest)
    - goto out_free;
    + goto out_free_hash;

    /* Save keys. */
    memcpy(state->master_key, &options[CILEN_MPPE],
    @@ -236,14 +236,12 @@ static void *mppe_alloc(unsigned char *options, int optlen)

    return (void *)state;

    +out_free_hash:
    + crypto_free_hash(state->sha1);
    +out_free_blkcipher:
    + crypto_free_blkcipher(state->arc4);
    out_free:
    - kfree(state->sha1_digest);
    - if (state->sha1)
    - crypto_free_hash(state->sha1);
    - if (state->arc4)
    - crypto_free_blkcipher(state->arc4);
    kfree(state);
    -out:
    return NULL;
    }

    --
    2.1.3


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