Re: [syzbot] Re: [syzbot] [net?] WARNING in nsim_udp_tunnel_set_port

[syzbot <syzbot+2e5de9e3ab986b71d2bf@syzkaller.appspotmail.com>]

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***

Subject: Re: [syzbot] [net?] WARNING in nsim_udp_tunnel_set_port
Author: kuba@kernel.org

On Wed, 15 Jan 2025 06:42:22 -0800 syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    63676eefb7a0 Merge tag 'sched_ext-for-6.13-rc5-fixes' of g..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1336e418580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=86dd15278dbfe19f
> dashboard link: https://syzkaller.appspot.com/bug?extid=2e5de9e3ab986b71d2bf
> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=17cfb1c4580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13ac4edf980000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/ba5dd9f6cf65/disk-63676eef.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/290bc4e6d798/vmlinux-63676eef.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/561f22e07925/bzImage-63676eef.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+2e5de9e3ab986b71d2bf@syzkaller.appspotmail.com

#syz test

diff --git a/drivers/net/netdevsim/udp_tunnels.c b/drivers/net/netdevsim/udp_tunnels.c
index 02dc3123eb6c..9c627433c34a 100644
--- a/drivers/net/netdevsim/udp_tunnels.c
+++ b/drivers/net/netdevsim/udp_tunnels.c
@@ -112,8 +112,8 @@ nsim_udp_tunnels_info_reset_write(struct file *file, const char __user *data,
 	struct net_device *dev = file->private_data;
 	struct netdevsim *ns = netdev_priv(dev);
 
-	memset(ns->udp_ports.ports, 0, sizeof(ns->udp_ports.__ports));
 	rtnl_lock();
+	memset(ns->udp_ports.ports, 0, sizeof(ns->udp_ports.__ports));
 	udp_tunnel_nic_reset_ntf(dev);
 	rtnl_unlock();