On Mon, 2017-10-09 at 14:14 +0200, Jason A. Donenfeld wrote: > 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.
I'm not necessarily sure it's _nice_, but I do think it doesn't matter, so that's just splitting hairs. If you do have a genl family with parallel_ops, you'd better be prepared to handle parallel things, and then this could also be in parallel :-) > 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: Jason A. Donenfeld <[email protected]> Reviewed-by: Johannes Berg <[email protected]> johannes
