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    Subject[PATCH 5.11 210/329] smc: disallow TCP_ULP in smc_setsockopt()
    Date
    From: Cong Wang <cong.wang@bytedance.com>

    [ Upstream commit 8621436671f3a4bba5db57482e1ee604708bf1eb ]

    syzbot is able to setup kTLS on an SMC socket which coincidentally
    uses sk_user_data too. Later, kTLS treats it as psock so triggers a
    refcnt warning. The root cause is that smc_setsockopt() simply calls
    TCP setsockopt() which includes TCP_ULP. I do not think it makes
    sense to setup kTLS on top of SMC sockets, so we should just disallow
    this setup.

    It is hard to find a commit to blame, but we can apply this patch
    since the beginning of TCP_ULP.

    Reported-and-tested-by: syzbot+b54a1ce86ba4a623b7f0@syzkaller.appspotmail.com
    Fixes: 734942cc4ea6 ("tcp: ULP infrastructure")
    Cc: John Fastabend <john.fastabend@gmail.com>
    Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
    Signed-off-by: Cong Wang <cong.wang@bytedance.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/smc/af_smc.c | 4 +++-
    1 file changed, 3 insertions(+), 1 deletion(-)

    diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
    index 47340b3b514f..cb23cca72c24 100644
    --- a/net/smc/af_smc.c
    +++ b/net/smc/af_smc.c
    @@ -2162,6 +2162,9 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
    struct smc_sock *smc;
    int val, rc;

    + if (level == SOL_TCP && optname == TCP_ULP)
    + return -EOPNOTSUPP;
    +
    smc = smc_sk(sk);

    /* generic setsockopts reaching us here always apply to the
    @@ -2186,7 +2189,6 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
    if (rc || smc->use_fallback)
    goto out;
    switch (optname) {
    - case TCP_ULP:
    case TCP_FASTOPEN:
    case TCP_FASTOPEN_CONNECT:
    case TCP_FASTOPEN_KEY:
    --
    2.30.2


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