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    Subject[PATCH 4.14 24/88] net: rds: fix memory leak in rds_recvmsg
    Date
    From: Pavel Skripkin <paskripkin@gmail.com>

    [ Upstream commit 49bfcbfd989a8f1f23e705759a6bb099de2cff9f ]

    Syzbot reported memory leak in rds. The problem
    was in unputted refcount in case of error.

    int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
    int msg_flags)
    {
    ...

    if (!rds_next_incoming(rs, &inc)) {
    ...
    }

    After this "if" inc refcount incremented and

    if (rds_cmsg_recv(inc, msg, rs)) {
    ret = -EFAULT;
    goto out;
    }
    ...
    out:
    return ret;
    }

    in case of rds_cmsg_recv() fail the refcount won't be
    decremented. And it's easy to see from ftrace log, that
    rds_inc_addref() don't have rds_inc_put() pair in
    rds_recvmsg() after rds_cmsg_recv()

    1) | rds_recvmsg() {
    1) 3.721 us | rds_inc_addref();
    1) 3.853 us | rds_message_inc_copy_to_user();
    1) + 10.395 us | rds_cmsg_recv();
    1) + 34.260 us | }

    Fixes: bdbe6fbc6a2f ("RDS: recv.c")
    Reported-and-tested-by: syzbot+5134cdf021c4ed5aaa5f@syzkaller.appspotmail.com
    Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
    Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>
    Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/rds/recv.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/net/rds/recv.c b/net/rds/recv.c
    index ef022d24f87a..a1b2bdab6655 100644
    --- a/net/rds/recv.c
    +++ b/net/rds/recv.c
    @@ -663,7 +663,7 @@ int rds_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,

    if (rds_cmsg_recv(inc, msg, rs)) {
    ret = -EFAULT;
    - goto out;
    + break;
    }

    rds_stats_inc(s_recv_delivered);
    --
    2.30.2
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