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* [PATCH] netfiler: protect nft_ct_pcpu_template_refcnt with mutex
@ 2021-08-10 12:55 Pavel Skripkin
  2021-08-10 12:59 ` [PATCH v2] netfilter: " Pavel Skripkin
  0 siblings, 1 reply; 4+ messages in thread
From: Pavel Skripkin @ 2021-08-10 12:55 UTC (permalink / raw)
  To: pablo, kadlec, fw, davem
  Cc: netfilter-devel, coreteam, netdev, linux-kernel, Pavel Skripkin,
	syzbot+649e339fa6658ee623d3

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>
---
 net/netfilter/nft_ct.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

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
-- 
2.32.0


^ permalink raw reply	[flat|nested] 4+ messages in thread

* [PATCH v2] netfilter: protect nft_ct_pcpu_template_refcnt with mutex
  2021-08-10 12:55 [PATCH] netfiler: protect nft_ct_pcpu_template_refcnt with mutex Pavel Skripkin
@ 2021-08-10 12:59 ` Pavel Skripkin
  2021-08-10 13:22   ` Florian Westphal
  2021-08-11  9:22   ` Pablo Neira Ayuso
  0 siblings, 2 replies; 4+ messages in thread
From: Pavel Skripkin @ 2021-08-10 12:59 UTC (permalink / raw)
  To: pablo, kadlec, fw, davem
  Cc: netfilter-devel, coreteam, netdev, linux-kernel, Pavel Skripkin,
	syzbot+649e339fa6658ee623d3

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>
---

Changes in v2:
	Fixed typo in title: netfiler -> netfilter

---
 net/netfilter/nft_ct.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

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
-- 
2.32.0


^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH v2] netfilter: protect nft_ct_pcpu_template_refcnt with mutex
  2021-08-10 12:59 ` [PATCH v2] netfilter: " Pavel Skripkin
@ 2021-08-10 13:22   ` Florian Westphal
  2021-08-11  9:22   ` Pablo Neira Ayuso
  1 sibling, 0 replies; 4+ messages in thread
From: Florian Westphal @ 2021-08-10 13:22 UTC (permalink / raw)
  To: Pavel Skripkin
  Cc: pablo, kadlec, fw, davem, netfilter-devel, coreteam, netdev,
	linux-kernel, syzbot+649e339fa6658ee623d3

Pavel Skripkin <paskripkin@gmail.com> wrote:
> 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>

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH v2] netfilter: protect nft_ct_pcpu_template_refcnt with mutex
  2021-08-10 12:59 ` [PATCH v2] netfilter: " Pavel Skripkin
  2021-08-10 13:22   ` Florian Westphal
@ 2021-08-11  9:22   ` Pablo Neira Ayuso
  1 sibling, 0 replies; 4+ messages in thread
From: Pablo Neira Ayuso @ 2021-08-11  9:22 UTC (permalink / raw)
  To: Pavel Skripkin
  Cc: kadlec, fw, davem, netfilter-devel, coreteam, netdev,
	linux-kernel, syzbot+649e339fa6658ee623d3

On Tue, Aug 10, 2021 at 03:59:20PM +0300, Pavel Skripkin wrote:
> 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.

Applied to nf.git, thanks

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-08-11  9:22 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-08-10 12:55 [PATCH] netfiler: protect nft_ct_pcpu_template_refcnt with mutex Pavel Skripkin
2021-08-10 12:59 ` [PATCH v2] netfilter: " Pavel Skripkin
2021-08-10 13:22   ` Florian Westphal
2021-08-11  9:22   ` Pablo Neira Ayuso

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