Re: [PATCH] sock: fix /proc/net/sockstat underflow in sk_clone_lock()

On 11/14/21 2:43 PM, Tetsuo Handa wrote:

On 2021/11/15 5:01, Eric Dumazet wrote:

quoted

On 11/13/21 10:02 PM, Tetsuo Handa wrote:

quoted

sk_clone_lock() needs to call get_net() and sock_inuse_inc() together, or

s/sock_inuse_inc/sock_inuse_add/

quoted

quoted

socket_seq_show() will underflow when __sk_free() from sk_free() from
sk_free_unlock_clone() is called.

IMO, a "sock_inuse_get() underflow" is a very different problem,

Yes, a different problem. I found this problem while trying to examine
https://syzkaller.appspot.com/bug?extid=694120e1002c117747ed where
somebody might be failing to call get_net() or we might be failing to
make sure that all timers are synchronously stopped before put_net().

quoted

I suspect this should be fixed with the following patch.

My patch addresses a permanent underflow problem which remains as long as
that namespace exists. Your patch addresses a temporal underflow problem
which happens due to calculating the sum without locks. Therefore, we can
apply both patches if we want.

I think your changelog is a bit confusing.

It would really help if you add the Fixes: tag, because if you do

1) It makes the patch much easier to understand, by reading again the the old patch.

2) We can tell if we can merge both fixes in the same submission (if they share the same bug origin)

Thanks !