[PATCH net] net: tun: unlink NAPI from device on destruction

[PATCH net] net: tun: unlink NAPI from device on destruction

[Jakub Kicinski]

Syzbot found a race between tun file and device destruction.
NAPIs live in struct tun_file which can get destroyed before
the netdev so we have to del them explicitly. The current
code is missing deleting the NAPI if the queue was detached
first.

Fixes: 943170998b20 ("tun: enable NAPI for TUN/TAP driver")
Reported-by: syzbot+b75c138e9286ac742647@syzkaller.appspotmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: peterpenkov96@gmail.com
CC: maheshb@google.com
---
 drivers/net/tun.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 87a635aac008..7fd0288c3789 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -727,6 +727,7 @@ static void tun_detach_all(struct net_device *dev)
 		sock_put(&tfile->sk);
 	}
 	list_for_each_entry_safe(tfile, tmp, &tun->disabled, next) {
+		tun_napi_del(tfile);
 		tun_enable_queue(tfile);
 		tun_queue_purge(tfile);
 		xdp_rxq_info_unreg(&tfile->xdp_rxq);
-- 
2.36.1

Re: [PATCH net] net: tun: unlink NAPI from device on destruction

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 22 Jun 2022 21:20:39 -0700 you wrote:
> Syzbot found a race between tun file and device destruction.
> NAPIs live in struct tun_file which can get destroyed before
> the netdev so we have to del them explicitly. The current
> code is missing deleting the NAPI if the queue was detached
> first.
> 
> Fixes: 943170998b20 ("tun: enable NAPI for TUN/TAP driver")
> Reported-by: syzbot+b75c138e9286ac742647@syzkaller.appspotmail.com
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> 
> [...]

Here is the summary with links:
  - [net] net: tun: unlink NAPI from device on destruction
    https://git.kernel.org/netdev/net/c/3b9bc84d3111

You are awesome, thank you!
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