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net/atm: sk_err_soft must be positive

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The sk_err and sk_err_soft fields are positive errno values and
userspace applications rely on this when using getsockopt(SO_ERROR).

ATM code places an -errno into sk_err_soft in sigd_send() and returns it
from svc_addparty()/svc_dropparty().

Although I am not familiar with ATM code I came to this conclusion
because:

1. sigd_send() msg->type cases as_okay and as_error both have:

   sk->sk_err = -msg->reply;

   while the as_addparty and as_dropparty cases have:

   sk->sk_err_soft = msg->reply;

   This is the source of the inconsistency.

2. svc_addparty() returns an -errno and assumes sk_err_soft is also an
   -errno:

       if (flags & O_NONBLOCK) {
           error = -EINPROGRESS;
           goto out;
       }
       ...
       error = xchg(&sk->sk_err_soft, 0);
   out:
       release_sock(sk);
       return error;

   This shows that sk_err_soft is indeed being treated as an -errno.

This patch ensures that sk_err_soft is always a positive errno.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Stefan Hajnoczi 2016-05-18 17:42:13 -07:00 committed by David S. Miller
parent bbf178e0a0
commit c685293aa3
2 changed files with 3 additions and 3 deletions
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2
net/atm/signaling.c
View File

@ -124,7 +124,7 @@ static int sigd_send(struct atm_vcc *vcc, struct sk_buff *skb)
break;
case as_addparty:
case as_dropparty:
sk->sk_err_soft = msg->reply;
sk->sk_err_soft = -msg->reply;
/* < 0 failure, otherwise ep_ref */
clear_bit(ATM_VF_WAITING, &vcc->flags);
break;

4
net/atm/svc.c
View File

@ -546,7 +546,7 @@ static int svc_addparty(struct socket *sock, struct sockaddr *sockaddr,
schedule();
}
finish_wait(sk_sleep(sk), &wait);
error = xchg(&sk->sk_err_soft, 0);
error = -xchg(&sk->sk_err_soft, 0);
out:
release_sock(sk);
return error;
@ -573,7 +573,7 @@ static int svc_dropparty(struct socket *sock, int ep_ref)
error = -EUNATCH;
goto out;
}
error = xchg(&sk->sk_err_soft, 0);
error = -xchg(&sk->sk_err_soft, 0);
out:
release_sock(sk);
return error;