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    Subject[PATCH 4.15 15/55] crypto: af_alg - whitelist mask and type
    Date
    4.15-stable review patch.  If anyone has any objections, please let me know.

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

    From: Stephan Mueller <smueller@chronox.de>

    commit bb30b8848c85e18ca7e371d0a869e94b3e383bdf upstream.

    The user space interface allows specifying the type and mask field used
    to allocate the cipher. Only a subset of the possible flags are intended
    for user space. Therefore, white-list the allowed flags.

    In case the user space caller uses at least one non-allowed flag, EINVAL
    is returned.

    Reported-by: syzbot <syzkaller@googlegroups.com>
    Signed-off-by: Stephan Mueller <smueller@chronox.de>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    crypto/af_alg.c | 10 ++++++----
    1 file changed, 6 insertions(+), 4 deletions(-)

    --- a/crypto/af_alg.c
    +++ b/crypto/af_alg.c
    @@ -150,7 +150,7 @@ EXPORT_SYMBOL_GPL(af_alg_release_parent)

    static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
    {
    - const u32 forbidden = CRYPTO_ALG_INTERNAL;
    + const u32 allowed = CRYPTO_ALG_KERN_DRIVER_ONLY;
    struct sock *sk = sock->sk;
    struct alg_sock *ask = alg_sk(sk);
    struct sockaddr_alg *sa = (void *)uaddr;
    @@ -158,6 +158,10 @@ static int alg_bind(struct socket *sock,
    void *private;
    int err;

    + /* If caller uses non-allowed flag, return error. */
    + if ((sa->salg_feat & ~allowed) || (sa->salg_mask & ~allowed))
    + return -EINVAL;
    +
    if (sock->state == SS_CONNECTED)
    return -EINVAL;

    @@ -176,9 +180,7 @@ static int alg_bind(struct socket *sock,
    if (IS_ERR(type))
    return PTR_ERR(type);

    - private = type->bind(sa->salg_name,
    - sa->salg_feat & ~forbidden,
    - sa->salg_mask & ~forbidden);
    + private = type->bind(sa->salg_name, sa->salg_feat, sa->salg_mask);
    if (IS_ERR(private)) {
    module_put(type->owner);
    return PTR_ERR(private);

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