I get a panic when I use ss -a and rmmod inet_diag at the
same time.
it's because netlink_dump use inet_diag_dump witch function
belongs to module inet_diag.
I search the codes and find many modules have the same problem.
We need add reference of the module witch the cb->dump belongs
to.
since CONFIG_NET is bool,so netlink_dump_start in rtnetlink.c
and genetlink.c will never trigger this problem.
Thanks for all help from Stephen,Jan and Eric.
Signed-off-by: Gao feng <gaofeng@xxxxxxxxxxxxxx>
---
include/linux/netlink.h | 4 ++++
net/netlink/af_netlink.c | 25 +++++++++++++++++++++----
2 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index f74dd13..a3641e3 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -232,6 +232,8 @@ struct netlink_callback {
struct netlink_callback *cb);
int (*done)(struct netlink_callback *cb);
void *data;
+ /* the module that dump function belong to */
+ struct module *module;
u16 family;
u16 min_dump_alloc;
unsigned int prev_seq, seq;
@@ -251,9 +253,11 @@ struct netlink_dump_control {
int (*dump)(struct sk_buff *skb, struct netlink_callback *);
int (*done)(struct netlink_callback*);
void *data;
+ struct module *module;
u16 min_dump_alloc;
};
+extern int netlink_dump_done(struct netlink_callback *cb);
extern int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
const struct nlmsghdr *nlh,
struct netlink_dump_control *control);
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 5270238..011091c 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1769,6 +1769,14 @@ errout_skb:
return err;
}
+int netlink_dump_done(struct netlink_callback *cb)
+{
+ if (cb->module)
+ module_put(cb->module);
+ return 0;
+}
+EXPORT_SYMBOL(netlink_dump_done);
+
int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
const struct nlmsghdr *nlh,
struct netlink_dump_control *control)
@@ -1786,6 +1794,7 @@ int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
cb->done = control->done;
cb->nlh = nlh;
cb->data = control->data;
+ cb->module = control->module;
cb->min_dump_alloc = control->min_dump_alloc;
atomic_inc(&skb->users);
cb->skb = skb;
@@ -1796,19 +1805,27 @@ int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
return -ECONNREFUSED;
}
nlk = nlk_sk(sk);
- /* A dump is in progress... */
+
mutex_lock(nlk->cb_mutex);
+ /* A dump is in progress... */
if (nlk->cb) {
mutex_unlock(nlk->cb_mutex);
netlink_destroy_callback(cb);
- sock_put(sk);
- return -EBUSY;
+ ret = -EBUSY;
+ goto out;
+ }
+ /* add reference of module witch cb->dump belone to */
+ if (cb->module && !try_module_get(cb->module)) {
+ mutex_unlock(nlk->cb_mutex);
+ ret = -EPROTONOSUPPORT;
+ goto out;
}
+
nlk->cb = cb;
mutex_unlock(nlk->cb_mutex);
ret = netlink_dump(sk);
-
+out:
sock_put(sk);
if (ret)
--
1.7.7.6
--
To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
