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authorPavel Skripkin <paskripkin@gmail.com>2021-08-10 15:59:20 +0300
committerPablo Neira Ayuso <pablo@netfilter.org>2021-08-11 11:22:19 +0200
commite3245a7b7b34bd2e97f744fd79463add6e9d41f4 (patch)
tree2ac2841ab3b72613e88ce2046d4d6ef9463bd7ef /net/netfilter
parent519133debcc19f5c834e7e28480b60bdc234fe02 (diff)
netfilter: nft_ct: protect nft_ct_pcpu_template_refcnt with mutex
Syzbot hit use-after-free in nf_tables_dump_sets. The problem was in missing lock protection for nft_ct_pcpu_template_refcnt. Before commit f102d66b335a ("netfilter: nf_tables: use dedicated mutex to guard transactions") all transactions were serialized by global mutex, but then global mutex was changed to local per netnamespace commit_mutex. This change causes use-after-free bug, when 2 netnamespaces concurently changing nft_ct_pcpu_template_refcnt without proper locking. Fix it by adding nft_ct_pcpu_mutex and protect all nft_ct_pcpu_template_refcnt changes with it. Fixes: f102d66b335a ("netfilter: nf_tables: use dedicated mutex to guard transactions") Reported-and-tested-by: syzbot+649e339fa6658ee623d3@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> Acked-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/netfilter')
-rw-r--r--net/netfilter/nft_ct.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c
index 337e22d8b40b..99b1de14ff7e 100644
--- a/net/netfilter/nft_ct.c
+++ b/net/netfilter/nft_ct.c
@@ -41,6 +41,7 @@ struct nft_ct_helper_obj {
#ifdef CONFIG_NF_CONNTRACK_ZONES
static DEFINE_PER_CPU(struct nf_conn *, nft_ct_pcpu_template);
static unsigned int nft_ct_pcpu_template_refcnt __read_mostly;
+static DEFINE_MUTEX(nft_ct_pcpu_mutex);
#endif
static u64 nft_ct_get_eval_counter(const struct nf_conn_counter *c,
@@ -525,8 +526,10 @@ static void __nft_ct_set_destroy(const struct nft_ctx *ctx, struct nft_ct *priv)
#endif
#ifdef CONFIG_NF_CONNTRACK_ZONES
case NFT_CT_ZONE:
+ mutex_lock(&nft_ct_pcpu_mutex);
if (--nft_ct_pcpu_template_refcnt == 0)
nft_ct_tmpl_put_pcpu();
+ mutex_unlock(&nft_ct_pcpu_mutex);
break;
#endif
default:
@@ -564,9 +567,13 @@ static int nft_ct_set_init(const struct nft_ctx *ctx,
#endif
#ifdef CONFIG_NF_CONNTRACK_ZONES
case NFT_CT_ZONE:
- if (!nft_ct_tmpl_alloc_pcpu())
+ mutex_lock(&nft_ct_pcpu_mutex);
+ if (!nft_ct_tmpl_alloc_pcpu()) {
+ mutex_unlock(&nft_ct_pcpu_mutex);
return -ENOMEM;
+ }
nft_ct_pcpu_template_refcnt++;
+ mutex_unlock(&nft_ct_pcpu_mutex);
len = sizeof(u16);
break;
#endif