From: Florian Westphal <fw@xxxxxxxxx>
Stas Nichiporovich reports oops in nf_nat_bysource_cmp(), trying to
access nf_conn struct at address 0xffffffffffffff50.
This is the result of fetching a null rhash list (struct embedded at
offset 176; 0 - 176 gets us ...fff50).
The problem is that conntrack entries are allocated from a
SLAB_DESTROY_BY_RCU cache, i.e. entries can be free'd and reused
on another cpu while nf nat bysource hash access the same conntrack entry.
Freeing is fine (we hold rcu read lock); zeroing rhlist_head isn't.
-> Move the rhlist struct outside of the memset()-inited area.
Fixes: 7c9664351980aaa6a ("netfilter: move nat hlist_head to nf_conn")
Reported-by: Stas Nichiporovich <stasn77@xxxxxxxxx>
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
include/net/netfilter/nf_conntrack.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index dc143ada9762..d9d52c020a70 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -100,6 +100,9 @@ struct nf_conn {
possible_net_t ct_net;
+#if IS_ENABLED(CONFIG_NF_NAT)
+ struct rhlist_head nat_bysource;
+#endif
/* all members below initialized via memset */
u8 __nfct_init_offset[0];
@@ -117,9 +120,6 @@ struct nf_conn {
/* Extensions */
struct nf_ct_ext *ext;
-#if IS_ENABLED(CONFIG_NF_NAT)
- struct rhlist_head nat_bysource;
-#endif
/* Storage reserved for other modules, must be the last member */
union nf_conntrack_proto proto;
};
--
2.1.4
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