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| author | Pavel Skripkin <paskripkin@gmail.com> | 2021-08-10 15:59:20 +0300 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2021-08-11 11:22:19 +0200 |
| commit | e3245a7b7b34bd2e97f744fd79463add6e9d41f4 (patch) | |
| tree | 2ac2841ab3b72613e88ce2046d4d6ef9463bd7ef /net | |
| parent | 519133debcc19f5c834e7e28480b60bdc234fe02 (diff) | |
| download | linux-e3245a7b7b34bd2e97f744fd79463add6e9d41f4.tar.gz linux-e3245a7b7b34bd2e97f744fd79463add6e9d41f4.tar.xz | |
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')
| -rw-r--r-- | net/netfilter/nft_ct.c | 9 |
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 |