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 /net/ipv4/arp.c | |
| 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 'net/ipv4/arp.c')
| -rw-r--r-- | net/ipv4/arp.c | 28 |
1 files changed, 17 insertions, 11 deletions
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index 1b74d3b64371..1d5675efcfbc 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -518,26 +518,32 @@ EXPORT_SYMBOL(arp_find); /* END OF OBSOLETE FUNCTIONS */ +struct neighbour *__arp_bind_neighbour(struct dst_entry *dst, __be32 nexthop) +{ + struct net_device *dev = dst->dev; + + if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) + nexthop = 0; + return __neigh_lookup_errno( +#if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE) + dev->type == ARPHRD_ATM ? + clip_tbl_hook : +#endif + &arp_tbl, &nexthop, dev); +} + int arp_bind_neighbour(struct dst_entry *dst) { struct net_device *dev = dst->dev; - struct neighbour *n = dst->neighbour; + struct neighbour *n = dst_get_neighbour(dst); if (dev == NULL) return -EINVAL; if (n == NULL) { - __be32 nexthop = ((struct rtable *)dst)->rt_gateway; - if (dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) - nexthop = 0; - n = __neigh_lookup_errno( -#if defined(CONFIG_ATM_CLIP) || defined(CONFIG_ATM_CLIP_MODULE) - dev->type == ARPHRD_ATM ? - clip_tbl_hook : -#endif - &arp_tbl, &nexthop, dev); + n = __arp_bind_neighbour(dst, ((struct rtable *)dst)->rt_gateway); if (IS_ERR(n)) return PTR_ERR(n); - dst->neighbour = n; + dst_set_neighbour(dst, n); } return 0; } |