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.
Thanks for all help from Stephen,Jan,Eric and Steffen.
Signed-off-by: Gao feng <gaofeng@xxxxxxxxxxxxxx>
---
include/linux/netlink.h | 6 +++++-
net/netlink/af_netlink.c | 25 +++++++++++++++++++++----
2 files changed, 26 insertions(+), 5 deletions(-)
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index f74dd13..381f7d6 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;
@@ -249,11 +251,13 @@ __nlmsg_put(struct sk_buff *skb, u32 pid, u32 seq, int type, int len, int flags)
struct netlink_dump_control {
int (*dump)(struct sk_buff *skb, struct netlink_callback *);
- int (*done)(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..3190dae 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1769,6 +1769,13 @@ errout_skb:
return err;
}
+int netlink_dump_done(struct netlink_callback *cb)
+{
+ 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 +1793,7 @@ 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 +1804,28 @@ 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 belong to */
+ if (!try_module_get(cb->module)) {
+ mutex_unlock(nlk->cb_mutex);
+ netlink_destroy_callback(cb);
+ 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
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