2021-07-14 03:28:54

by Dongliang Mu

Subject: [PATCH v3] audit: fix memory leak in nf_tables_commit

In nf_tables_commit, if nf_tables_commit_audit_alloc fails, it does not
free the adp variable.

Fix this by adding nf_tables_commit_audit_free which frees
the linked list with the head node adl.

backtrace:
kmalloc include/linux/slab.h:591 [inline]
kzalloc include/linux/slab.h:721 [inline]
nf_tables_commit_audit_alloc net/netfilter/nf_tables_api.c:8439 [inline]
nf_tables_commit+0x16e/0x1760 net/netfilter/nf_tables_api.c:8508
nfnetlink_rcv_batch+0x512/0xa80 net/netfilter/nfnetlink.c:562
nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:634 [inline]
nfnetlink_rcv+0x1fa/0x220 net/netfilter/nfnetlink.c:652
netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
netlink_unicast+0x2c7/0x3e0 net/netlink/af_netlink.c:1340
netlink_sendmsg+0x36b/0x6b0 net/netlink/af_netlink.c:1929
sock_sendmsg_nosec net/socket.c:702 [inline]
sock_sendmsg+0x56/0x80 net/socket.c:722

Reported-by: syzbot <[email protected]>
Reported-by: kernel test robot <[email protected]>
Fixes: c520292f29b8 ("audit: log nftables configuration change events once per table")
Signed-off-by: Dongliang Mu <[email protected]>
---
v1->v2: fix the compile issue
v2->v3: modify the added function to a new name
net/netfilter/nf_tables_api.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 390d4466567f..7f45b291be13 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -8444,6 +8444,16 @@ static int nf_tables_commit_audit_alloc(struct list_head *adl,
return 0;
}

+static void nf_tables_commit_audit_free(struct list_head *adl)
+{
+ struct nft_audit_data *adp, *adn;
+
+ list_for_each_entry_safe(adp, adn, adl, list) {
+ list_del(&adp->list);
+ kfree(adp);
+ }
+}
+
static void nf_tables_commit_audit_collect(struct list_head *adl,
struct nft_table *table, u32 op)
{
@@ -8508,6 +8518,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
ret = nf_tables_commit_audit_alloc(&adl, trans->ctx.table);
if (ret) {
nf_tables_commit_chain_prepare_cancel(net);
+ nf_tables_commit_audit_free(&adl);
return ret;
}
if (trans->msg_type == NFT_MSG_NEWRULE ||
@@ -8517,6 +8528,7 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
ret = nf_tables_commit_chain_prepare(net, chain);
if (ret < 0) {
nf_tables_commit_chain_prepare_cancel(net);
+ nf_tables_commit_audit_free(&adl);
return ret;
}
}
--
2.25.1

2021-07-17 00:24:53

by Pablo Neira Ayuso

Subject: Re: [PATCH v3] audit: fix memory leak in nf_tables_commit

On Wed, Jul 14, 2021 at 11:27:03AM +0800, Dongliang Mu wrote:
> In nf_tables_commit, if nf_tables_commit_audit_alloc fails, it does not
> free the adp variable.
>
> Fix this by adding nf_tables_commit_audit_free which frees
> the linked list with the head node adl.
>
> backtrace:
> kmalloc include/linux/slab.h:591 [inline]
> kzalloc include/linux/slab.h:721 [inline]
> nf_tables_commit_audit_alloc net/netfilter/nf_tables_api.c:8439 [inline]
> nf_tables_commit+0x16e/0x1760 net/netfilter/nf_tables_api.c:8508
> nfnetlink_rcv_batch+0x512/0xa80 net/netfilter/nfnetlink.c:562
> nfnetlink_rcv_skb_batch net/netfilter/nfnetlink.c:634 [inline]
> nfnetlink_rcv+0x1fa/0x220 net/netfilter/nfnetlink.c:652
> netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
> netlink_unicast+0x2c7/0x3e0 net/netlink/af_netlink.c:1340
> netlink_sendmsg+0x36b/0x6b0 net/netlink/af_netlink.c:1929
> sock_sendmsg_nosec net/socket.c:702 [inline]
> sock_sendmsg+0x56/0x80 net/socket.c:722

Applied, thanks.