Hi, did anyone request a CVE yet?
Ciao, Marcus On Sat, Mar 25, 2017 at 01:10:57AM +0100, Solar Designer wrote: > On Fri, Mar 24, 2017 at 03:21:06PM -0700, Eric Dumazet wrote: > > Looks easy enough to fix ? > > Oh. Probably. Thanks. Need to test, but I guess you already did? > > > diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c > > index > > 2af6244b83e27ae384e96cf071c10c5a89674804..ccfbce13a6333a65dab64e4847dd510dfafb1b43 > > 100644 > > --- a/net/ipv4/ping.c > > +++ b/net/ipv4/ping.c > > @@ -156,17 +156,18 @@ int ping_hash(struct sock *sk) > > void ping_unhash(struct sock *sk) > > { > > struct inet_sock *isk = inet_sk(sk); > > + > > pr_debug("ping_unhash(isk=%p,isk->num=%u)\n", isk, isk->inet_num); > > + write_lock_bh(&ping_table.lock); > > if (sk_hashed(sk)) { > > - write_lock_bh(&ping_table.lock); > > hlist_nulls_del(&sk->sk_nulls_node); > > sk_nulls_node_init(&sk->sk_nulls_node); > > sock_put(sk); > > isk->inet_num = 0; > > isk->inet_sport = 0; > > sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1); > > - write_unlock_bh(&ping_table.lock); > > } > > + write_unlock_bh(&ping_table.lock); > > } > > EXPORT_SYMBOL_GPL(ping_unhash); > > FWIW, in Pavel's original implementation for 2.4.32 (unused), this was: > > static void ping_v4_unhash(struct sock *sk) > { > DEBUG(("ping_v4_unhash(sk=%p,sk->num=%u)\n", sk, sk->num)); > write_lock_bh(&ping_hash_lock); > if (sk->pprev) { > if (sk->next) > sk->next->pprev = sk->pprev; > *sk->pprev = sk->next; > sk->pprev = NULL; > sk->num = 0; > sock_prot_dec_use(sk->prot); > __sock_put(sk); > } > write_unlock_bh(&ping_hash_lock); > } > > Looks like the erroneous optimization (not expecting concurrent activity > on the same socket?) was introduced during conversion to 2.6's hlists. > > So far this cursed function had 3 bugs, two of them security (including > this one) and one probably benign (or if not, then effectively a subset > of this bug as it performed some unneeded / stale debugging work before > acquiring the lock), with all 3 introduced in forward-porting. Maybe > the nature of forward-porting activity makes people relatively > inattentive ("compiles with the new interfaces and still works? must be > correct"), compared to when writing new code. > > Anyhow, I share some responsibility for this mess, for having advocated > this patch being forward-ported and merged back then. I still like > having this functionality and its userspace security benefits... but I > don't like the kernel bugs. > > Alexander > -- Marcus Meissner,SUSE LINUX GmbH; Maxfeldstrasse 5; D-90409 Nuernberg; Zi. 3.1-33,+49-911-740 53-432,,serv=loki,mail=wotan,type=real <meiss...@suse.de>