[Patch net-next] vsock: always call vsock_init_tables()

[Patch net-next] vsock: always call vsock_init_tables()

[Cong Wang]

Although CONFIG_VSOCKETS_DIAG depends on CONFIG_VSOCKETS,
vsock_init_tables() is not always called, it is called only
if other modules call its caller. Therefore if we only
enable CONFIG_VSOCKETS_DIAG, it would crash kernel on uninitialized
vsock_bind_table.

This patch fixes it by moving vsock_init_tables() to its own
module_init().

Fixes: 413a4317aca7 ("VSOCK: add sock_diag interface")
Reported-by: syzkaller bot
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Jorgen Hansen <jhansen@vmware.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
---
 net/vmw_vsock/af_vsock.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 98359c19522f..5d28abf87fbf 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -195,7 +195,7 @@ static int vsock_auto_bind(struct vsock_sock *vsk)
 	return __vsock_bind(sk, &local_addr);
 }
 
-static void vsock_init_tables(void)
+static int __init vsock_init_tables(void)
 {
 	int i;
 
@@ -204,6 +204,7 @@ static void vsock_init_tables(void)
 
 	for (i = 0; i < ARRAY_SIZE(vsock_connected_table); i++)
 		INIT_LIST_HEAD(&vsock_connected_table[i]);
+	return 0;
 }
 
 static void __vsock_insert_bound(struct list_head *list,
@@ -1957,8 +1958,6 @@ int __vsock_core_init(const struct vsock_transport *t, struct module *owner)
 	vsock_proto.owner = owner;
 	transport = t;
 
-	vsock_init_tables();
-
 	vsock_device.minor = MISC_DYNAMIC_MINOR;
 	err = misc_register(&vsock_device);
 	if (err) {
@@ -2019,6 +2018,8 @@ const struct vsock_transport *vsock_core_get_transport(void)
 }
 EXPORT_SYMBOL_GPL(vsock_core_get_transport);
 
+module_init(vsock_init_tables);
+
 MODULE_AUTHOR("VMware, Inc.");
 MODULE_DESCRIPTION("VMware Virtual Socket Family");
 MODULE_VERSION("1.0.2.0-k");
-- 
2.13.0

Re: [Patch net-next] vsock: always call vsock_init_tables()

[Stefan Hajnoczi]

On Tue, Oct 24, 2017 at 03:30:37PM -0700, Cong Wang wrote:
> Although CONFIG_VSOCKETS_DIAG depends on CONFIG_VSOCKETS,
> vsock_init_tables() is not always called, it is called only
> if other modules call its caller. Therefore if we only
> enable CONFIG_VSOCKETS_DIAG, it would crash kernel on uninitialized
> vsock_bind_table.
> 
> This patch fixes it by moving vsock_init_tables() to its own
> module_init().
> 
> Fixes: 413a4317aca7 ("VSOCK: add sock_diag interface")
> Reported-by: syzkaller bot
> Cc: Stefan Hajnoczi <stefanha@redhat.com>
> Cc: Jorgen Hansen <jhansen@vmware.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
> ---
>  net/vmw_vsock/af_vsock.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)

Thank you, Cong Wang!  I was just trying to figure out the syzkaller bug
report and you've already fixed it :).  The patch looks good.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

Re: [Patch net-next] vsock: always call vsock_init_tables()

[David Miller]

From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Tue, 24 Oct 2017 15:30:37 -0700

> Although CONFIG_VSOCKETS_DIAG depends on CONFIG_VSOCKETS,
> vsock_init_tables() is not always called, it is called only
> if other modules call its caller. Therefore if we only
> enable CONFIG_VSOCKETS_DIAG, it would crash kernel on uninitialized
> vsock_bind_table.
> 
> This patch fixes it by moving vsock_init_tables() to its own
> module_init().
> 
> Fixes: 413a4317aca7 ("VSOCK: add sock_diag interface")
> Reported-by: syzkaller bot
> Cc: Stefan Hajnoczi <stefanha@redhat.com>
> Cc: Jorgen Hansen <jhansen@vmware.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>

Applied.