On Mon, May 16, 2016 at 2:28 AM, Herbert Xu <herb...@gondor.apana.org.au> wrote: > On Sun, May 15, 2016 at 12:06:46PM -0700, Cong Wang wrote: >> >> Similar to what Richard reported, I think the problem is cb->skb, >> which is exposed to other thread since cb is per netlink socket >> (cb = &nlk->cb). IOW, the cb->skb is freed by one thread at the >> end of netlink_dump() meanwhile the other thread is still using >> it via NETLINK_CB(cb->skb).portid. > > You're on the right track. I think what's happening is that the > second thread is starting a new dump and the first thread ends up > freeing the skb of the new dump and leaking the old skb. > > ---8<--- > Subject: netlink: Fix dump skb leak/double free > > When we free cb->skb after a dump, we do it after releasing the > lock. This means that a new dump could have started in the time > being and we'll end up freeing their skb instead of ours. > > This patch saves the skb and module before we unlock so we free > the right memory.
Yeah, this fix makes more sense than mine. > > Fixes: 16b304f3404f ("netlink: Eliminate kmalloc in netlink dump operation.") > Reported-by: Baozeng Ding <splovi...@gmail.com> > Signed-off-by: Herbert Xu <herb...@gondor.apana.org.au> Acked-by: Cong Wang <xiyou.wangc...@gmail.com> Thanks.