path: root/net
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authorEric Dumazet <eric.dumazet@gmail.com>2010-09-21 21:17:32 +0000
committerDavid S. Miller <davem@davemloft.net>2010-09-22 13:13:33 -0700
commit15cdeadaa5d76009e20c7792aed69f5a73808f97 (patch)
tree11eb05f550c046b3099d52df146948dce0c12635 /net
parentb46ffb854554ff939701bdd492b81558da5706fc (diff)
netfilter: fix a race in nf_ct_ext_create()
As soon as rcu_read_unlock() is called, there is no guarantee current thread can safely derefence t pointer, rcu protected. Fix is to copy t->alloc_size in a temporary variable. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
1 files changed, 3 insertions, 1 deletions
diff --git a/net/netfilter/nf_conntrack_extend.c b/net/netfilter/nf_conntrack_extend.c
index 7dcf7a404190..8d9e4c949b96 100644
--- a/net/netfilter/nf_conntrack_extend.c
+++ b/net/netfilter/nf_conntrack_extend.c
@@ -48,15 +48,17 @@ nf_ct_ext_create(struct nf_ct_ext **ext, enum nf_ct_ext_id id, gfp_t gfp)
unsigned int off, len;
struct nf_ct_ext_type *t;
+ size_t alloc_size;
t = rcu_dereference(nf_ct_ext_types[id]);
BUG_ON(t == NULL);
off = ALIGN(sizeof(struct nf_ct_ext), t->align);
len = off + t->len;
+ alloc_size = t->alloc_size;
- *ext = kzalloc(t->alloc_size, gfp);
+ *ext = kzalloc(alloc_size, gfp);
if (!*ext)
return NULL;

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