diff options
| author | Eric Dumazet <edumazet@google.com> | 2015-11-29 19:37:57 -0800 |
|---|---|---|
| committer | Mister Oyster <oysterized@gmail.com> | 2016-12-11 13:24:42 +0100 |
| commit | 1776a7190214a2baefc033ffc651eca2b4152e5b (patch) | |
| tree | aa11acebbcb08d0398fe6d59a6a0b09df85f3705 /include/net/ipv6.h | |
| parent | ac094a58d17aa221423c18a004cf7f8747e62298 (diff) | |
ipv6: add complete rcu protection around np->opt
[ Upstream commit 45f6fad84cc305103b28d73482b344d7f5b76f39 ]
This patch addresses multiple problems :
UDP/RAW sendmsg() need to get a stable struct ipv6_txoptions
while socket is not locked : Other threads can change np->opt
concurrently. Dmitry posted a syzkaller
(http://github.com/google/syzkaller) program desmonstrating
use-after-free.
Starting with TCP/DCCP lockless listeners, tcp_v6_syn_recv_sock()
and dccp_v6_request_recv_sock() also need to use RCU protection
to dereference np->opt once (before calling ipv6_dup_options())
This patch adds full RCU protection to np->opt
BUG: 28746669
Change-Id: I207da29ac48bb6dd7c40d65f9e27c4e3ff508da0
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Pierre Imai <imaipi@google.com>
Diffstat (limited to 'include/net/ipv6.h')
| -rw-r--r-- | include/net/ipv6.h | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/include/net/ipv6.h b/include/net/ipv6.h index 8645f1bc8..21f2b904a 100644 --- a/include/net/ipv6.h +++ b/include/net/ipv6.h @@ -203,6 +203,7 @@ extern rwlock_t ip6_ra_lock; */ struct ipv6_txoptions { + atomic_t refcnt; /* Length of this structure */ int tot_len; @@ -215,7 +216,7 @@ struct ipv6_txoptions { struct ipv6_opt_hdr *dst0opt; struct ipv6_rt_hdr *srcrt; /* Routing Header */ struct ipv6_opt_hdr *dst1opt; - + struct rcu_head rcu; /* Option buffer, as read by IPV6_PKTOPTIONS, starts here. */ }; @@ -246,6 +247,24 @@ struct ipv6_fl_socklist { struct rcu_head rcu; }; +static inline struct ipv6_txoptions *txopt_get(const struct ipv6_pinfo *np) +{ + struct ipv6_txoptions *opt; + + rcu_read_lock(); + opt = rcu_dereference(np->opt); + if (opt && !atomic_inc_not_zero(&opt->refcnt)) + opt = NULL; + rcu_read_unlock(); + return opt; +} + +static inline void txopt_put(struct ipv6_txoptions *opt) +{ + if (opt && atomic_dec_and_test(&opt->refcnt)) + kfree_rcu(opt, rcu); +} + extern struct ip6_flowlabel *fl6_sock_lookup(struct sock *sk, __be32 label); extern struct ipv6_txoptions *fl6_merge_options(struct ipv6_txoptions * opt_space, struct ip6_flowlabel * fl, |