net: hsr: Use the seqnr lock for frames received via interlink port.

syzbot reported that the seqnr_lock is not acquire for frames received
over the interlink port. In the interlink case a new seqnr is generated
and assigned to the frame.
Frames, which are received over the slave port have already a sequence
number assigned so the lock is not required.

Acquire the hsr_priv::seqnr_lock during in the invocation of
hsr_forward_skb() if a packet has been received from the interlink port.

Reported-by: syzbot+3d602af7549af539274e@syzkaller.appspotmail.com
Closes: https://groups.google.com/g/syzkaller-bugs/c/KppVvGviGg4/m/EItSdCZdBAAJ
Fixes: 5055cccfc2d1c ("net: hsr: Provide RedBox support (HSR-SAN)")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Tested-by: Lukasz Majewski <lukma@denx.de>
Link: https://patch.msgid.link/20240906132816.657485-2-bigeasy@linutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/hsr/hsr_slave.c b/net/hsr/hsr_slave.c
index af6cf64a00e081c777db5f7786e8a27ea6f62e14..464f683e016dbba659ac0e4f2e02306bfd016ad9 100644 (file)
--- a/net/hsr/hsr_slave.c
+++ b/net/hsr/hsr_slave.c
@@ -67,7 +67,16 @@ static rx_handler_result_t hsr_handle_frame(struct sk_buff **pskb)
                skb_set_network_header(skb, ETH_HLEN + HSR_HLEN);
        skb_reset_mac_len(skb);
 
-       hsr_forward_skb(skb, port);
+       /* Only the frames received over the interlink port will assign a
+        * sequence number and require synchronisation vs other sender.
+        */
+       if (port->type == HSR_PT_INTERLINK) {
+               spin_lock_bh(&hsr->seqnr_lock);
+               hsr_forward_skb(skb, port);
+               spin_unlock_bh(&hsr->seqnr_lock);
+       } else {
+               hsr_forward_skb(skb, port);
+       }
 
 finish_consume:
        return RX_HANDLER_CONSUMED;