4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Pablo Neira Ayuso <[email protected]> [ Upstream commit 35d0ac9070ef619e3bf44324375878a1c540387b ] If the element exists and no NLM_F_EXCL is specified, do not bump set->nelems, otherwise we leak one set element slot. This problem amplifies if the set is full since the abort path always decrements the counter for the -ENFILE case too, giving one spare extra slot. Fix this by moving set->nelems update to nft_add_set_elem() after successful element insertion. Moreover, remove the element if the set is full so there is no need to rely on the abort path to undo things anymore. Fixes: c016c7e45ddf ("netfilter: nf_tables: honor NLM_F_EXCL flag in set element insertion") Signed-off-by: Pablo Neira Ayuso <[email protected]> Signed-off-by: Sasha Levin <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- net/netfilter/nf_tables_api.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -3637,10 +3637,18 @@ static int nft_add_set_elem(struct nft_c goto err5; } + if (set->size && + !atomic_add_unless(&set->nelems, 1, set->size + set->ndeact)) { + err = -ENFILE; + goto err6; + } + nft_trans_elem(trans) = elem; list_add_tail(&trans->list, &ctx->net->nft.commit_list); return 0; +err6: + set->ops->remove(set, &elem); err5: kfree(trans); err4: @@ -3687,15 +3695,9 @@ static int nf_tables_newsetelem(struct n return -EBUSY; nla_for_each_nested(attr, nla[NFTA_SET_ELEM_LIST_ELEMENTS], rem) { - if (set->size && - !atomic_add_unless(&set->nelems, 1, set->size + set->ndeact)) - return -ENFILE; - err = nft_add_set_elem(&ctx, set, attr, nlh->nlmsg_flags); - if (err < 0) { - atomic_dec(&set->nelems); + if (err < 0) break; - } } return err; }
