From 1689f25924ada8fe14a4a82c38925d04994c7142 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Wed, 28 Jun 2023 16:24:27 +0200 Subject: netfilter: nf_tables: report use refcount overflow Overflow use refcount checks are not complete. Add helper function to deal with object reference counter tracking. Report -EMFILE in case UINT_MAX is reached. nft_use_dec() splats in case that reference counter underflows, which should not ever happen. Add nft_use_inc_restore() and nft_use_dec_restore() which are used to restore reference counter from error and abort paths. Use u32 in nft_flowtable and nft_object since helper functions cannot work on bitfields. Remove the few early incomplete checks now that the helper functions are in place and used to check for refcount overflow. Fixes: 96518518cc41 ("netfilter: add nftables") Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_objref.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'net/netfilter/nft_objref.c') diff --git a/net/netfilter/nft_objref.c b/net/netfilter/nft_objref.c index a48dd5b5d45b..509011b1ef59 100644 --- a/net/netfilter/nft_objref.c +++ b/net/netfilter/nft_objref.c @@ -41,8 +41,10 @@ static int nft_objref_init(const struct nft_ctx *ctx, if (IS_ERR(obj)) return -ENOENT; + if (!nft_use_inc(&obj->use)) + return -EMFILE; + nft_objref_priv(expr) = obj; - obj->use++; return 0; } @@ -72,7 +74,7 @@ static void nft_objref_deactivate(const struct nft_ctx *ctx, if (phase == NFT_TRANS_COMMIT) return; - obj->use--; + nft_use_dec(&obj->use); } static void nft_objref_activate(const struct nft_ctx *ctx, @@ -80,7 +82,7 @@ static void nft_objref_activate(const struct nft_ctx *ctx, { struct nft_object *obj = nft_objref_priv(expr); - obj->use++; + nft_use_inc_restore(&obj->use); } static const struct nft_expr_ops nft_objref_ops = { -- cgit v1.2.3-70-g09d2