diff options
| author | Eric Dumazet <eric.dumazet@gmail.com> | 2012-02-09 16:13:19 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-02-13 11:06:13 -0800 |
| commit | 8a533666d1591cf4ea596c6bd710e2fe682cb56a (patch) | |
| tree | 0c525703fd834499c659490b3cb38835fde14f51 /include | |
| parent | 323a479328cbc2fb5cf647790f7414ca570a577b (diff) | |
net: fix NULL dereferences in check_peer_redir()
[ Upstream commit d3aaeb38c40e5a6c08dd31a1b64da65c4352be36, along
with dependent backports of commits:
69cce1d1404968f78b177a0314f5822d5afdbbfb
9de79c127cccecb11ae6a21ab1499e87aa222880
218fa90f072e4aeff9003d57e390857f4f35513e
580da35a31f91a594f3090b7a2c39b85cb051a12
f7e57044eeb1841847c24aa06766c8290c202583
e049f28883126c689cf95859480d9ee4ab23b7fa ]
Gergely Kalman reported crashes in check_peer_redir().
It appears commit f39925dbde778 (ipv4: Cache learned redirect
information in inetpeer.) added a race, leading to possible NULL ptr
dereference.
Since we can now change dst neighbour, we should make sure a reader can
safely use a neighbour.
Add RCU protection to dst neighbour, and make sure check_peer_redir()
can be called safely by different cpus in parallel.
As neighbours are already freed after one RCU grace period, this patch
should not add typical RCU penalty (cache cold effects)
Many thanks to Gergely for providing a pretty report pointing to the
bug.
Reported-by: Gergely Kalman <synapse@hippy.csoma.elte.hu>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/arp.h | 1 | ||||
| -rw-r--r-- | include/net/dst.h | 27 |
2 files changed, 25 insertions, 3 deletions
diff --git a/include/net/arp.h b/include/net/arp.h index 91f0568a04e..fb0eb9048b1 100644 --- a/include/net/arp.h +++ b/include/net/arp.h @@ -16,6 +16,7 @@ extern void arp_send(int type, int ptype, __be32 dest_ip, const unsigned char *dest_hw, const unsigned char *src_hw, const unsigned char *th); extern int arp_bind_neighbour(struct dst_entry *dst); +extern struct neighbour *__arp_bind_neighbour(struct dst_entry *dst, __be32 nexthop); extern int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir); extern void arp_ifdown(struct net_device *dev); diff --git a/include/net/dst.h b/include/net/dst.h index e12ddfb9eb1..d0201340bee 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -37,7 +37,7 @@ struct dst_entry { unsigned long _metrics; unsigned long expires; struct dst_entry *path; - struct neighbour *neighbour; + struct neighbour __rcu *_neighbour; struct hh_cache *hh; #ifdef CONFIG_XFRM struct xfrm_state *xfrm; @@ -86,6 +86,21 @@ struct dst_entry { }; }; +static inline struct neighbour *dst_get_neighbour(struct dst_entry *dst) +{ + return rcu_dereference(dst->_neighbour); +} + +static inline struct neighbour *dst_get_neighbour_raw(struct dst_entry *dst) +{ + return rcu_dereference_raw(dst->_neighbour); +} + +static inline void dst_set_neighbour(struct dst_entry *dst, struct neighbour *neigh) +{ + rcu_assign_pointer(dst->_neighbour, neigh); +} + extern u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old); extern const u32 dst_default_metrics[RTAX_MAX]; @@ -371,8 +386,14 @@ static inline void dst_rcu_free(struct rcu_head *head) static inline void dst_confirm(struct dst_entry *dst) { - if (dst) - neigh_confirm(dst->neighbour); + if (dst) { + struct neighbour *n; + + rcu_read_lock(); + n = dst_get_neighbour(dst); + neigh_confirm(n); + rcu_read_unlock(); + } } static inline void dst_link_failure(struct sk_buff *skb) |