Re: [PATCH] net: qrtr: fix null-ptr-deref in qrtr_ns_remove

[Qinglang Miao]

I sent a v2 on this one because of the redundant braces in 
qrtr_proto_init, sorry for the noise.

在 2021/1/5 10:40, Qinglang Miao 写道:
A null-ptr-deref bug is reported by Hulk Robot like this:
--------------
KASAN: null-ptr-deref in range [0x0000000000000128-0x000000000000012f]
Call Trace:
qrtr_ns_remove+0x22/0x40 [ns]
qrtr_proto_fini+0xa/0x31 [qrtr]
__x64_sys_delete_module+0x337/0x4e0
do_syscall_64+0x34/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x468ded
--------------
When qrtr_ns_init fails in qrtr_proto_init, qrtr_ns_remove which would
be called later on would raise a null-ptr-deref because qrtr_ns.workqueue
has been destroyed.

Fix it by making qrtr_ns_init have a return value and adding a check in
qrtr_proto_init.

Reported-by: Hulk Robot <hul...@huawei.com>
Signed-off-by: Qinglang Miao <miaoqingl...@huawei.com>
---
  net/qrtr/ns.c   |  7 ++++---
  net/qrtr/qrtr.c | 14 +++++++++++---
  net/qrtr/qrtr.h |  2 +-
  3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/net/qrtr/ns.c b/net/qrtr/ns.c
index 56aaf8cb6..8d00dfe81 100644
--- a/net/qrtr/ns.c
+++ b/net/qrtr/ns.c
@@ -755,7 +755,7 @@ static void qrtr_ns_data_ready(struct sock *sk)
        queue_work(qrtr_ns.workqueue, &qrtr_ns.work);
  }
  
-void qrtr_ns_init(void)
+int qrtr_ns_init(void)
  {
        struct sockaddr_qrtr sq;
        int ret;
@@ -766,7 +766,7 @@ void qrtr_ns_init(void)
        ret = sock_create_kern(&init_net, AF_QIPCRTR, SOCK_DGRAM,
                               PF_QIPCRTR, &qrtr_ns.sock);
        if (ret < 0)
-               return;
+               return ret;
  
  	ret = kernel_getsockname(qrtr_ns.sock, (struct sockaddr *)&sq);
        if (ret < 0) {
@@ -797,12 +797,13 @@ void qrtr_ns_init(void)
        if (ret < 0)
                goto err_wq;
  
-	return;
+       return 0;
  
  err_wq:
        destroy_workqueue(qrtr_ns.workqueue);
  err_sock:
        sock_release(qrtr_ns.sock);
+       return ret;
  }
  EXPORT_SYMBOL_GPL(qrtr_ns_init);
  
diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
index f4ab3ca6d..95533e451 100644
--- a/net/qrtr/qrtr.c
+++ b/net/qrtr/qrtr.c
@@ -1288,12 +1288,20 @@ static int __init qrtr_proto_init(void)
  
  	rc = sock_register(&qrtr_family);
        if (rc) {
-               proto_unregister(&qrtr_proto);
-               return rc;
+               goto err_proto;
        }
  
-	qrtr_ns_init();
+       rc = qrtr_ns_init();
+       if (rc) {
+               goto err_sock;
+       } >
+       return 0;
+
+err_sock:
+       sock_unregister(qrtr_family.family);
+err_proto:
+       proto_unregister(&qrtr_proto);
        return rc;
  }
  postcore_initcall(qrtr_proto_init);
diff --git a/net/qrtr/qrtr.h b/net/qrtr/qrtr.h
index dc2b67f17..3f2d28696 100644
--- a/net/qrtr/qrtr.h
+++ b/net/qrtr/qrtr.h
@@ -29,7 +29,7 @@ void qrtr_endpoint_unregister(struct qrtr_endpoint *ep);
  
  int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len);
  
-void qrtr_ns_init(void);
+int qrtr_ns_init(void);
  
  void qrtr_ns_remove(void);