[PATCH] decnet: fix shutdown parameter checking

The allowed value of "how" is SHUT_RD/SHUT_WR/SHUT_RDWR (0/1/2),
rather than SHUTDOWN_MASK (3).

Signed-off-by: Xi Wang <xi.wang@gmail.com>
---
 net/decnet/af_decnet.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/decnet/af_decnet.c b/net/decnet/af_decnet.c
index 2ba1a28..307c322 100644
--- a/net/decnet/af_decnet.c
+++ b/net/decnet/af_decnet.c

@@ -1313,10 +1313,10 @@ static int dn_shutdown(struct socket *sock, int how)
 	if (scp->state == DN_O)
 		goto out;
 
-	if (how != SHUTDOWN_MASK)
+	if (how != SHUT_RDWR)
 		goto out;
 
-	sk->sk_shutdown = how;
+	sk->sk_shutdown = SHUTDOWN_MASK;
 	dn_destroy_sock(sk);
 	err = 0;
 

-- 
1.7.9.5

On Sun, 2012-08-26 at 22:37 -0400, Xi Wang wrote:

The allowed value of "how" is SHUT_RD/SHUT_WR/SHUT_RDWR (0/1/2),
rather than SHUTDOWN_MASK (3).

Signed-off-by: Xi Wang <xi.wang@gmail.com>

Acked-by: Steven Whitehouse <redacted>

Although it could be argued that we should also continue to accept the
value 3 just in case there is any userland software out there which
sends that value,

Steve.

From: Steven Whitehouse <redacted>
Date: Mon, 27 Aug 2012 10:16:41 +0100

On Sun, 2012-08-26 at 22:37 -0400, Xi Wang wrote:

quoted

The allowed value of "how" is SHUT_RD/SHUT_WR/SHUT_RDWR (0/1/2),
rather than SHUTDOWN_MASK (3).

Signed-off-by: Xi Wang <xi.wang@gmail.com>

Acked-by: Steven Whitehouse <redacted>

Applied to net-next.

Although it could be argued that we should also continue to accept the
value 3 just in case there is any userland software out there which
sends that value,

True, but this is a rather standard BSD socket interface with a very
specific small set of legitimate input parameters.  Allowing
deviation, even for compatability for specific protocols, is largely
unwise.

Hi,

On Fri, 2012-08-31 at 15:57 -0400, David Miller wrote:

From: Steven Whitehouse <redacted>
Date: Mon, 27 Aug 2012 10:16:41 +0100

quoted

On Sun, 2012-08-26 at 22:37 -0400, Xi Wang wrote:

quoted

The allowed value of "how" is SHUT_RD/SHUT_WR/SHUT_RDWR (0/1/2),
rather than SHUTDOWN_MASK (3).

Signed-off-by: Xi Wang <xi.wang@gmail.com>

Acked-by: Steven Whitehouse <redacted>

Applied to net-next.

quoted

Although it could be argued that we should also continue to accept the
value 3 just in case there is any userland software out there which
sends that value,

True, but this is a rather standard BSD socket interface with a very
specific small set of legitimate input parameters.  Allowing
deviation, even for compatability for specific protocols, is largely
unwise.

Yes, I'd agree on the whole, and certainly if this was a recent
addition. However since this code has been around for somewhere close to
16 years now, I'd say that means that either (a) nobody calls shutdown
for DECnet or (b) existing users are buggy too.

We do have a precedent for this kind of compatibility, such as the AX.25
use of SOCK_SEQPACKET.

However, I'm not overly worried and we'll soon know if it will cause any
problems or not,

Steve.

From: Steven Whitehouse <redacted>
Date: Wed, 05 Sep 2012 09:37:56 +0100

However, I'm not overly worried and we'll soon know if it will cause any
problems or not,

You can be sure that if we get real bug reports due to this change, I will
revert it back to how it was before.