From: Pablo Neira Ayuso pablo@netfilter.org
commit 05907f10e235680cc7fb196810e4ad3215d5e648 upstream.
This patch fixes a race condition.
nft_rhash_update() might fail for two reasons:
- Element already exists in the hashtable. - Another packet won race to insert an entry in the hashtable.
In both cases, new() has already bumped the counter via atomic_add_unless(), therefore, decrement the set element counter.
Fixes: 22fe54d5fefc ("netfilter: nf_tables: add support for dynamic set updates") Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netfilter/nft_set_hash.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/net/netfilter/nft_set_hash.c +++ b/net/netfilter/nft_set_hash.c @@ -127,6 +127,7 @@ static bool nft_rhash_update(struct nft_ /* Another cpu may race to insert the element with the same key */ if (prev) { nft_set_elem_destroy(set, he, true); + atomic_dec(&set->nelems); he = prev; }
@@ -136,6 +137,7 @@ out:
err2: nft_set_elem_destroy(set, he, true); + atomic_dec(&set->nelems); err1: return false; }