• Jason A. Donenfeld's avatar
    netlink: do not set cb_running if dump's start() errs · 41c87425
    Jason A. Donenfeld authored
    It turns out that multiple places can call netlink_dump(), which means
    it's still possible to dereference partially initialized values in
    dump() that were the result of a faulty returned start().
    
    This fixes the issue by calling start() _before_ setting cb_running to
    true, so that there's no chance at all of hitting the dump() function
    through any indirect paths.
    
    It also moves the call to start() to be when the mutex is held. This has
    the nice side effect of serializing invocations to start(), which is
    likely desirable anyway. It also prevents any possible other races that
    might come out of this logic.
    
    In testing this with several different pieces of tricky code to trigger
    these issues, this commit fixes all avenues that I'm aware of.
    Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
    Cc: Johannes Berg <johannes@sipsolutions.net>
    Reviewed-by: default avatarJohannes Berg <johannes@sipsolutions.net>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    41c87425
af_netlink.c 63.6 KB