commit cf5000a7787cbc10341091d37245a42c119d26c5 upstream.
When more than 255 elements expired we're supposed to switch to a new gc container structure.
This never happens: u8 type will wrap before reaching the boundary and nft_trans_gc_space() always returns true.
This means we recycle the initial gc container structure and lose track of the elements that came before.
While at it, don't deref 'gc' after we've passed it to call_rcu.
Fixes: 5f68718b34a5 ("netfilter: nf_tables: GC transaction API to avoid race with control plane") Reported-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org --- include/net/netfilter/nf_tables.h | 2 +- net/netfilter/nf_tables_api.c | 10 ++++++++-- 2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index 84fd4cd7fc83..ee86f78bf93e 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -1440,7 +1440,7 @@ struct nft_trans_gc { struct net *net; struct nft_set *set; u32 seq; - u8 count; + u16 count; void *priv[NFT_TRANS_GC_BATCHCOUNT]; struct rcu_head rcu; }; diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 6676fbe6aeba..616961ce6ac5 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -7089,12 +7089,15 @@ static int nft_trans_gc_space(struct nft_trans_gc *trans) struct nft_trans_gc *nft_trans_gc_queue_async(struct nft_trans_gc *gc, unsigned int gc_seq, gfp_t gfp) { + struct nft_set *set; + if (nft_trans_gc_space(gc)) return gc;
+ set = gc->set; nft_trans_gc_queue_work(gc);
- return nft_trans_gc_alloc(gc->set, gc_seq, gfp); + return nft_trans_gc_alloc(set, gc_seq, gfp); } EXPORT_SYMBOL_GPL(nft_trans_gc_queue_async);
@@ -7111,15 +7114,18 @@ EXPORT_SYMBOL_GPL(nft_trans_gc_queue_async_done);
struct nft_trans_gc *nft_trans_gc_queue_sync(struct nft_trans_gc *gc, gfp_t gfp) { + struct nft_set *set; + if (WARN_ON_ONCE(!lockdep_commit_lock_is_held(gc->net))) return NULL;
if (nft_trans_gc_space(gc)) return gc;
+ set = gc->set; call_rcu(&gc->rcu, nft_trans_gc_trans_free);
- return nft_trans_gc_alloc(gc->set, 0, gfp); + return nft_trans_gc_alloc(set, 0, gfp); } EXPORT_SYMBOL_GPL(nft_trans_gc_queue_sync);