2022-11-04 11:18:09

by shaozhengchao

Subject: [PATCH net] wifi: mac80211: fix WARNING in ieee80211_link_info_change_notify()

Syz reports the following WARNING:
wlan0: Failed check-sdata-in-driver check, flags: 0x0
WARNING: CPU: 3 PID: 5384 at net/mac80211/main.c:287
ieee80211_link_info_change_notify+0x1c2/0x230
Modules linked in:
RIP: 0010:ieee80211_link_info_change_notify+0x1c2/0x230
Call Trace:
<TASK>
ieee80211_set_mcast_rate+0x3e/0x50
nl80211_set_mcast_rate+0x316/0x650
genl_family_rcv_msg_doit+0x20b/0x300
genl_rcv_msg+0x39f/0x6a0
netlink_rcv_skb+0x13b/0x3b0
genl_rcv+0x24/0x40
netlink_unicast+0x4a2/0x740
netlink_sendmsg+0x83e/0xce0
sock_sendmsg+0xc5/0x100
____sys_sendmsg+0x583/0x690
___sys_sendmsg+0xe8/0x160
__sys_sendmsg+0xbf/0x160
do_syscall_64+0x35/0x80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
</TASK>

The execution process is as follows:
Thread A:
ieee80211_open()
ieee80211_do_open()
drv_add_interface() //set IEEE80211_SDATA_IN_DRIVER flag
...
cfg80211_shutdown_all_interfaces()
...
ieee80211_stop()
ieee80211_do_stop()
drv_remove_interface() //clear flag
...
nl80211_set_mcast_rate()
ieee80211_set_mcast_rate()
ieee80211_link_info_change_notify()
check_sdata_in_driver() //WARNING because flag is cleared

When the wlan device stops, the IEEE80211_SDATA_IN_ DRIVER flag is cleared
after the interface is removed. And then after the set mcast rate command
is executed, a WARNING is generated because the flag bit is cleared.

Fixes: 591e73ee3f73 ("wifi: mac80211: properly skip link info driver update")
Reported-by: [email protected]
Signed-off-by: Zhengchao Shao <[email protected]>
---
net/mac80211/main.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 46f3eddc2388..8a727b532f77 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -284,6 +284,9 @@ void ieee80211_link_info_change_notify(struct ieee80211_sub_if_data *sdata,
if (!changed || sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
return;

+ if (!ieee80211_sdata_running(sdata))
+ return;
+
if (!check_sdata_in_driver(sdata))
return;

--
2.17.1

2022-12-01 14:15:54

by Johannes Berg

Subject: Re: [PATCH net] wifi: mac80211: fix WARNING in ieee80211_link_info_change_notify()

On Fri, 2022-11-04 at 19:08 +0800, Zhengchao Shao wrote:
>
> The execution process is as follows:
> Thread A:
> ieee80211_open()
> ieee80211_do_open()
> drv_add_interface() //set IEEE80211_SDATA_IN_DRIVER flag
> ...
> cfg80211_shutdown_all_interfaces()
> ...
> ieee80211_stop()
> ieee80211_do_stop()
> drv_remove_interface() //clear flag
> ...
> nl80211_set_mcast_rate()

How is that possible after the interface is no longer running? That
seems to be the issue? I suppose that should be annotated to not be
allowed?

johannes