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authorLiping Zhang <zlpnobody@gmail.com>2017-05-07 22:01:56 +0800
committerPablo Neira Ayuso <pablo@netfilter.org>2017-05-15 12:42:29 +0200
commit9338d7b4418e9996a7642867d8f6b482a6040ed6 (patch)
tree5bf37ab11070434ed04c1bcfe12194925bfffd25 /include
parentd91fc59cd77c719f33eda65c194ad8f95a055190 (diff)
netfilter: nfnl_cthelper: reject del request if helper obj is in use
We can still delete the ct helper even if it is in use, this will cause a use-after-free error. In more detail, I mean: # nfct helper add ssdp inet udp # iptables -t raw -A OUTPUT -p udp -j CT --helper ssdp # nfct helper delete ssdp //--> oops, succeed! BUG: unable to handle kernel paging request at 000026ca IP: 0x26ca [...] Call Trace: ? ipv4_helper+0x62/0x80 [nf_conntrack_ipv4] nf_hook_slow+0x21/0xb0 ip_output+0xe9/0x100 ? ip_fragment.constprop.54+0xc0/0xc0 ip_local_out+0x33/0x40 ip_send_skb+0x16/0x80 udp_send_skb+0x84/0x240 udp_sendmsg+0x35d/0xa50 So add reference count to fix this issue, if ct helper is used by others, reject the delete request. Apply this patch: # nfct helper delete ssdp nfct v1.4.3: netlink error: Device or resource busy Signed-off-by: Liping Zhang <zlpnobody@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'include')
-rw-r--r--include/net/netfilter/nf_conntrack_helper.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h
index c1c12411103a..c519bb5b5bb8 100644
--- a/include/net/netfilter/nf_conntrack_helper.h
+++ b/include/net/netfilter/nf_conntrack_helper.h
@@ -9,6 +9,7 @@
#ifndef _NF_CONNTRACK_HELPER_H
#define _NF_CONNTRACK_HELPER_H
+#include <linux/refcount.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_extend.h>
#include <net/netfilter/nf_conntrack_expect.h>
@@ -26,6 +27,7 @@ struct nf_conntrack_helper {
struct hlist_node hnode; /* Internal use. */
char name[NF_CT_HELPER_NAME_LEN]; /* name of the module */
+ refcount_t refcnt;
struct module *me; /* pointer to self */
const struct nf_conntrack_expect_policy *expect_policy;