> -----Original Message-----
> From: Zhengchao Shao <shaozhengchao@xxxxxxxxxx>
> Sent: Wednesday, October 26, 2022 10:47 AM
> To: linux-wireless@xxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; johannes@xxxxxxxxxxxxxxxx;
> davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx
> Cc: toke@xxxxxxxxxx; alexander@xxxxxxxxxxxxxx; nbd@xxxxxxxx; weiyongjun1@xxxxxxxxxx;
> yuehaibing@xxxxxxxxxx; shaozhengchao@xxxxxxxxxx
> Subject: [PATCH net,v2] wifi: mac80211: fix general-protection-fault in ieee80211_subif_start_xmit()
>
> When device is running and the interface status is changed, the gpf issue
> is triggered. The problem triggering process is as follows:
> Thread A: Thread B
> ieee80211_runtime_change_iftype() process_one_work()
> ... ...
> ieee80211_do_stop() ...
> ... ...
> sdata->bss = NULL ...
> ... ieee80211_subif_start_xmit()
> ieee80211_multicast_to_unicast
> //!sdata->bss->multicast_to_unicast
> cause gpf issue
>
> When the interface status is changed, the sending queue continues to send
> packets. After the bss is set to NULL, the bss is accessed. As a result,
> this causes a general-protection-fault issue.
>
> The following is the stack information:
> general protection fault, probably for non-canonical address
> 0xdffffc000000002f: 0000 [#1] PREEMPT SMP KASAN
> KASAN: null-ptr-deref in range [0x0000000000000178-0x000000000000017f]
> Workqueue: mld mld_ifc_work
> RIP: 0010:ieee80211_subif_start_xmit+0x25b/0x1310
> Call Trace:
> <TASK>
> dev_hard_start_xmit+0x1be/0x990
> __dev_queue_xmit+0x2c9a/0x3b60
> ip6_finish_output2+0xf92/0x1520
> ip6_finish_output+0x6af/0x11e0
> ip6_output+0x1ed/0x540
> mld_sendpack+0xa09/0xe70
> mld_ifc_work+0x71c/0xdb0
> process_one_work+0x9bf/0x1710
> worker_thread+0x665/0x1080
> kthread+0x2e4/0x3a0
> ret_from_fork+0x1f/0x30
> </TASK>
>
> Fixes: f856373e2f31 ("wifi: mac80211: do not wake queues on a vif that is being stopped")
> Reported-by: syzbot+c6e8fca81c294fd5620a@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Zhengchao Shao <shaozhengchao@xxxxxxxxxx>
> ---
> net/mac80211/tx.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
> index a364148149f9..c38485f39d2b 100644
> --- a/net/mac80211/tx.c
> +++ b/net/mac80211/tx.c
> @@ -4418,6 +4418,11 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
> if (likely(!is_multicast_ether_addr(eth->h_dest)))
> goto normal;
>
> + if (unlikely(!ieee80211_sdata_running(sdata))) {
> + kfree_skb(skb);
> + return NETDEV_TX_OK;
> + }
> +
The indent looks odd. It seems like you use spaces instead of tabs?
> if (unlikely(ieee80211_multicast_to_unicast(skb, dev))) {
> struct sk_buff_head queue;
>
> --
> 2.17.1
>
>
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